To find out how many yogurt cups Mary sold, you can calculate \( \frac{5}{8} \) of 40 cups.
First, multiply 40 by \( \frac{5}{8} \):
\[ \text{Cups sold} = 40 \times \frac{5}{8} \]
Calculating this step-by-step:
- \( 40 \div 8 = 5 \)
- \( 5 \times 5 = 25 \)
So, Mary sold 25 yogurt cups.