To find out how many costumes Scott can make with 12 yards of fabric, we need to divide the total amount of fabric by the amount of fabric needed for each costume.
The calculation is as follows:
\[ \text{Number of costumes} = \frac{\text{Total fabric}}{\text{Fabric per costume}} = \frac{12 \text{ yards}}{\frac{3}{4} \text{ yard}} \]
To divide by a fraction, we multiply by its reciprocal:
\[ \frac{12}{\frac{3}{4}} = 12 \times \frac{4}{3} \]
Calculating this gives:
\[ 12 \times \frac{4}{3} = \frac{48}{3} = 16 \]
So, Scott can make 16 costumes.