Answer:
7
Step-by-step explanation:
Make the fractions have a denominator of 20.
2/5 times the top and bottom by 4 (because 5 times 4 = 20) = 8/20
So 8 socks are white
1/4 times 5 = 5/20
So 5 socks are black
Add them and subtract from 20 to get the number of gray socks
20-13=7
