A product is sold for $240 after a 20% discount. What was the original price?

Here are the solutions to the questions:

Q1) A product is sold for $240 after a 20% discount. What was the original price?

Step 1: Determine the percentage of the original price represented by the discounted price. A 20% discount means the selling price is $100\% - 20\% = 80\%$ of the original price.

Step 2: Set up an equation to find the original price. Let $P$ be the original price. $0.80 \times P = \$240$

Step 3: Solve for $P$. $P = \frac{\$240}{0.80}$ $P = \$300$ The original price was \boxed{\300}$.

Q2) If 5 pens cost $12.50, what is the cost of 8 pens?

Step 1: Calculate the cost of one pen. $\text{Cost per pen} = \frac{\$12.50}{5 pens}$ $\text{Cost per pen} = \$2.50 \text{ per pen}$

Step 2: Calculate the cost of 8 pens. $\text{Cost of 8 pens} = \$2.50/pen \times 8 \text{ pens}$ $\text{Cost of 8 pens} = \$20.00$ The cost of 8 pens is \boxed{\20}$.

Q3) A train travels at 90 km/h. How far will it go in 2 hours and 30 minutes?

Step 1: Convert the total time to hours. $30 minutes = \frac{30}{60} hours = 0.5 \text{ hours}$ $\text{Total time} = 2 hours + 0.5 hours = 2.5 \text{ hours}$

Step 2: Use the formula Distance = Speed $\times$ Time. $\text{Distance} = 90 km/h \times 2.5 \text{ h}$ $\text{Distance} = 225 \text{ km}$ The train will go $\boxed{225 km}$.

Q4) A man spends 3/5 of his salary. If he earns $2,500 monthly, how much does he save?

Step 1: Determine the fraction of salary saved. If he spends $\frac{3}{5}$ of his salary, he saves the remaining fraction. $\text{Fraction saved} = 1 - \frac{3}{5}$ $\text{Fraction saved} = \frac{5}{5} - \frac{3}{5}$ $\text{Fraction saved} = \frac{2}{5}$

Step 2: Calculate the amount saved. $\text{Amount saved} = \frac{2}{5} \times \$2,500$ $\text{Amount saved} = \frac{2 \times \$2,500}{5}$ $\text{Amount saved} = \frac{\$5,000}{5}$ $\text{Amount saved} = \$1,000$ He saves \boxed{\1,000}$.