#### Answer

It takes 65 yards of material to make 20 dresses.

#### Work Step by Step

It takes 3$\frac{1}{4}$ yards of material to make one dress, which is equal to $\frac{13}{4}$. To make 20 dresses, we multiply $\frac{13}{4}$ by 20.
So, $\frac{13}{4}$ $\times$ 20 = $\frac{13\ \times\ 20}{4}$ =
Factor the numerator and the denominator:
$\frac{13\ \times\ 4\ \times\ 5}{4}$ =
Cancel the common factors in the numerator and the denominator to obtain:
13 $\times$ 5 = 65 yards of material