Write down the place value of 3 in the number 4329.

The digit 3 is in the hundreds place.

$$
3 \times 100 = 300
$$
The place value of 3 is $\boxed{\text{300}}$.

The perimeter $P$ of a rectangle with length $l$ and width $w$ is given by $P = 2(l + w)$.

$$
P = 2(8 \text{ m} + 6 \text{ m})
$$

$$
P = 2(14 \text{ m})
$$
$$
P = 28 \text{ m}
$$
The perimeter of the garden is $\boxed{\text{28 m}}$.

$$
2y + 3 - 3 = 11 - 3
$$
$$
2y = 8
$$

$$
\frac{2y}{2} = \frac{8}{2}
$$
$$
y = 4
$$
The value of $y$ is $\boxed{4}$.

There are 4 ball icons.

$$
\text{Total balls} = 4 \times 8
$$
$$
\text{Total balls} = 32
$$
There are $\boxed{\text{32 balls}}$ represented.

The least common multiple of 2 and 3 is 6.

$$
\frac{1}{2} = \frac{1 \times 3}{2 \times 3} = \frac{3}{6}
$$
$$
\frac{1}{3} = \frac{1 \times 2}{3 \times 2} = \frac{2}{6}
$$

$$
\frac{3}{6} + \frac{2}{6} = \frac{3+2}{6} = \frac{5}{6}
$$
The sum is $\boxed{\frac{5}{6}}$.

Each number is 2 less than the previous number ($20-2=18$, $18-2=16$, $16-2=14$).

$$
14 - 2 = 12
$$
The next number in the sequence is $\boxed{12}$.

$$
\text{Number of boys} = \text{Total pupils} - \text{Number of girls}
$$
$$
\text{Number of boys} = 84 - 47
$$

$$
\text{Number of boys} = 37
$$
There are $\boxed{\text{37 boys}}$ in the class.