To determine how many birdhouses Chelsea can build, we need to divide the total length of the board by the length of wood needed for each birdhouse.
Chelsea has a 12-foot board. Each birdhouse requires \( \frac{3}{4} \) foot of wood.
First, let's convert \( \frac{3}{4} \) foot to a decimal for easier calculations:
\[ \frac{3}{4} = 0.75 \text{ foot} \]
Now, we divide the total length of the board by the length needed for each birdhouse:
\[ \text{Number of birdhouses} = \frac{12 \text{ feet}}{0.75 \text{ foot/birdhouse}} \]
Now we can calculate:
\[ \frac{12}{0.75} = 12 \div 0.75 = 16 \]
Therefore, Chelsea can build 16 birdhouses.
The correct response is: 16 birdhouses.