Answer 2/5. It says there are 5 people and 3 of them have done their hw and 2 have not cause 5-3=2.
V = area of the base × height / 3
V = 6 × 15 / 3 = 30 cubic inches
They have the same denominator, so you can subtract them right away, but first make them into improper fractions
5 3/8 = 43/8
3 5/8 = 29/8
43/8 - 29/8 = 14/8
Reduced, 7/4 which is 1 3/4
I hope that helps!