To find out how many birdhouses Chelsea can build, we need to divide the total length of the wood she has by the length of wood needed for each birdhouse.
Chelsea has a 12-foot board of wood, and each birdhouse requires \( \frac{3}{4} \) foot of wood.
We can calculate the number of birdhouses using the formula:
\[ \text{Number of birdhouses} = \frac{\text{Total length of wood}}{\text{Length of wood per birdhouse}} = \frac{12 \text{ feet}}{\frac{3}{4} \text{ foot}} \]
To divide by a fraction, we can multiply by its reciprocal:
\[ \frac{12}{\frac{3}{4}} = 12 \times \frac{4}{3} = \frac{48}{3} = 16 \]
Thus, Chelsea can build 16 birdhouses.