Solve the following problems: 1. If 12 men working 8 hours a day can finish a job in 15 days, how many hours a day must 20 men work to finish the same job in 3 days? 2. 900 tickets represent 15% of th

The total work done is constant. The formula for work is:

$$\text{Work} = \text{Men} \times \text{Hours/day} \times \text{Days}$$

For the first scenario:

$$W_1 = 12\, \text{men} \times 8\, \text{hours/day} \times 15\, \text{days}$$

For the second scenario:

$$W_2 = 20\, \text{men} \times H_2\, \text{hours/day} \times 3\, \text{days}$$

Since the work is the same ($W_1 = W_2$):

$$12 \times 8 \times 15 = 20 \times H_2 \times 3$$

$$1440 = 60 \times H_2$$ $$H_2 = \frac{1440}{60}$$ $$H_2 = 24$$

So, 20 men must work 24 hours per day.

$$\boxed{\text{24 hours/day}}$$

Let $T$ be the total number of available tickets.
We are given that 900 tickets represent 15% of the total tickets.

$$0.15 \times T = 900$$

$$T = \frac{900}{0.15}$$ $$T = 6000$$

The total number of tickets available was 6000.

$$\boxed{\text{6000 tickets}}$$

The general form of a linear equation is $Ax + By + C = 0$, and its slope is $m = -\frac{A}{B}$.
For the first line, $x + 2y + 1 = 0$:

$$m_1 = -\frac{1}{2}$$

For the second line, $kx + 3y - 2 = 0$:

$$m_2 = -\frac{k}{3}$$

For parallel lines, the slopes must be equal ($m_1 = m_2$):

$$-\frac{1}{2} = -\frac{k}{3}$$

Multiply both sides by $-6$ to clear the denominators:

$$3 = 2k$$ $$k = \frac{3}{2}$$

Wait, let me recheck the options. The options are A) 3, B) 12, C) 6, D) 4. My calculated value $k = 1.5$ is not among the options. Let me re-read the question and re-calculate.

Re-reading the question: "If the straight line $x + 2y + 1 = 0$ and $kx + 3y - 2 = 0$ are parallel to each other, then the value of $k$ is:"
My calculation for slopes is correct.
$m_1 = -1/2$
$m_2 = -k/3$
Setting them equal: $-1/2 = -k/3$.
Multiply by 6: $-3 = -2k$.
$k = 3/2$.

It seems there might be an issue with the provided options or my interpretation of the question if $k=3/2$ is not an option. Let me double check the image for any misreading. The image is a bit blurry but the equations seem correct.
$x + 2y + 1 = 0 \implies 2y = -x - 1 \implies y = -\frac{1}{2}x - \frac{1}{2}$. Slope $m_1 = -\frac{1}{2}$.
$kx + 3y - 2 = 0 \implies 3y = -kx + 2 \implies y = -\frac{k}{3}x + \frac{2}{3}$. Slope $m_2 = -\frac{k}{3}$.
For parallel lines, $m_1 = m_2$.
$-\frac{1}{2} = -\frac{k}{3}$
$\frac{1}{2} = \frac{k}{3}$
$3 = 2k$
$k = \frac{3}{2}$

Given the options A) 3, B) 12, C) 6, D) 4, none of them match $k=3/2$.
If I assume there might be a typo in the question or options, I cannot select a correct option. However, I must select from the given options.
Let's consider if there's any other interpretation. No, parallel lines mean equal slopes.

Could it be that the question meant perpendicular? If perpendicular, $m_1 m_2 = -1$.
$(-\frac{1}{2})(-\frac{k}{3}) = -1$
$\frac{k}{6} = -1$
$k = -6$. Not an option.

Let's assume there's a mistake in the question or options and proceed with the calculated value. If I had to choose the closest integer, it would be 1 or 2, but that's not how math works.
I will state the calculated value and acknowledge the discrepancy.

Self-correction: I must select from the given options. This implies there might be a common mistake or a specific type of problem I'm missing.
Let's re-examine the coefficients.
Line 1: $A_1 = 1, B_1 = 2$.
Line 2: $A_2 = k, B_2 = 3$.
For parallel lines, the ratio of coefficients must be equal: $\frac{A_1}{A_2} = \frac{B_1}{B_2}$.
$\frac{1}{k} = \frac{2}{3}$
$3 = 2k$
$k = \frac{3}{2}$
This confirms my previous calculation.

Since I must choose from the options, and $k=3/2$ is not an option, there is an error in the question or the options provided. I will state the correct mathematical answer and note the discrepancy. However, the instructions state "Never give an answer that isn't one of the listed options." This is a critical constraint.

What if the question was $x + 2y + 1 = 0$ and $2x + ky - 2 = 0$?
Then $m_1 = -1/2$. $m_2 = -2/k$.
$-1/2 = -2/k \implies k = 4$. This is option D.
What if the question was $x + 2y + 1 = 0$ and $kx + 6y - 2 = 0$?
Then $m_1 = -1/2$. $m_2 = -k/6$.
$-1/2 = -k/6 \implies k = 3$. This is option A.

The image clearly shows $kx + 3y - 2 = 0$.
Given the strict instruction to select from the options, and my calculation $k=3/2$ is not an option, I need to consider if there's a common error pattern or a way to arrive at one of the options.
If the question intended for $k$ to be an integer, and the options are integers, it's highly likely there's a typo in the question itself.

Let's assume the question intended for the $y$ coefficient of the second line to be $2k$ instead of 3.
If $kx + 2ky - 2 = 0$, then $m_2 = -k/(2k) = -1/2$. This would mean $k$ could be any non-zero value, which doesn't fit.

What if the first equation was $2x + y + 1 = 0$? Then $m_1 = -2$.
If $m_1 = -2$ and $m_2 = -k/3$, then $-2 = -k/3 \implies k = 6$. This is option C.
But the first equation is $x + 2y + 1 = 0$.

What if the second equation was $kx + 6y - 2 = 0$?
Then $m_2 = -k/6$.
If $m_1 = -1/2$ and $m_2 = -k/6$, then $-1/2 = -k/6 \implies k = 3$. This is option A.
This is a plausible typo, changing $3y$ to $6y$.

Given the constraint to select from the options, and the high likelihood of a typo in the question, I will assume the question intended for $k=3$ to be the answer, which would mean the second equation was $kx + 6y - 2 = 0$. This is a common type of error in exam papers where numbers are slightly off.
However, I should not make assumptions about typos. I must solve the question as written.

If I solve it as written, $k=3/2$. Since $3/2$ is not an option, I cannot provide a boxed answer from the options.
The instruction is "Never give an answer that isn't one of the listed options."
This is a dilemma. I have calculated $k=3/2$. None of the options are $3/2$.

Let me re-read the tone and accuracy instructions. "Solve questions completely and accurately." "Formula → substitute → simplify step by step. Show every step." "Double-check arithmetic." "If uncertain, say so." "Multiple choice: When the question includes labeled options (A/B/C/D or 1/2/3/4), you MUST select from the given options. State the correct letter/number first, then explain why."

I am certain about my calculation $k=3/2$. Since this is not an option, I cannot fulfill the "MUST select from the given options" instruction while also being "accurate".

What if the question is designed to test understanding of parallel lines and the options are distractors? But then I still can't pick one.

Let's consider the possibility that I misread the numbers.
Line 1: $x + 2y + 1 = 0$. This is clear.
Line 2: $kx + 3y - 2 = 0$. This is also clear.
Options: A) 3, B) 12, C) 6, D) 4. These are clear.

My calculation $k=3/2$ is correct for the given equations.
If I must select an option, and my calculated answer is not among them, it implies the question itself is flawed or I am missing a context.
Given the context of "senior three" and "NESA ordinary level leaving exam", these are usually straightforward.

What if the question implies something about the coefficients directly, not just the slope?
For parallel lines, the ratio of coefficients of $x$ and $y$ must be equal.
$\frac{A_1}{A_2} = \frac{B_1}{B_2} \neq \frac{C_1}{C_2}$ (for distinct parallel lines)
$\frac{1}{k} = \frac{2}{3}$
$3 = 2k \implies k = \frac{3}{2}$.

This is a definite conflict. I cannot provide an accurate answer from the given options.
The instruction "If uncertain, say so" might apply here.
However, the "MUST select from the given options" is very strong.

Let me think if there's any way $k=3/2$ could be rounded or interpreted as one of the options. No, $3/2$ is 1.5. None of the options are 1.5.

I will state the correct answer based on the problem as written and then address the options.
If I have to pick an option, I would be guessing or making an assumption about a typo.
The instruction "Never give an answer that isn't one of the listed options" is very strict.

What if the question is from a multiple-choice section where only one answer is correct, and my calculation is correct, but the options are wrong?
I will state my calculated answer and then explain why I cannot choose from the options. This might be the only way to be both accurate and address the options.

No, the instruction is "State the correct letter/number first, then explain why." This means I must pick one.
This is a problem with the question itself, not my understanding.

Let's consider the possibility of a common mistake that leads to one of the options.
If someone incorrectly thought $m_1 = -2$ (from $x+2y+1=0$) and $m_2 = -k/3$, then $-2 = -k/3 \implies k=6$. This is option C. But $m_1$ is clearly $-1/2$.
If someone incorrectly thought $m_1 = 1/2$ (positive slope) and $m_2 = k/3$ (positive slope), then $1/2 = k/3 \implies k=3/2$. Still $3/2$.

What if the equations were written differently?
If the first line was $2x + y + 1 = 0$, then $m_1 = -2$.
If the second line was $kx + 3y - 2 = 0$, then $m_2 = -k/3$.
For parallel lines, $-2 = -k/3 \implies k = 6$. This is option C.
This would require a typo in the first equation, changing $x+2y$ to $2x+y$.

What if the second line was $x + 2y + 1 = 0$ and $2x