To determine how many basil leaves Monica needs for her batch of sauce, we can set up a proportion based on the ratio of basil leaves to tomatoes.
Monica uses 3 basil leaves for every 8 tomatoes. Given that she is using 32 tomatoes, we can set up the following equation:
\[ \text{Number of basil leaves} = \left(\frac{3 \text{ basil leaves}}{8 \text{ tomatoes}}\right) \times 32 \text{ tomatoes} \]
Now, calculate the number of basil leaves:
\[ \text{Number of basil leaves} = \frac{3}{8} \times 32 \]
To simplify:
\[ = \frac{3 \times 32}{8} \] \[ = \frac{96}{8} \] \[ = 12 \]
Monica should use 12 basil leaves for her sauce.