Question

A gift box is in the shape of a trapezoidal prism with base lengths of 7 inches and 5 inches and a height of 4 inches. The height of the gift box is 8 inches. What is the volume of the gift box?

Answer 1

First of all there are multiple formula's to get the volume of a trapezoidal prism:

V=(1/2 * (base1 + base2) * h) * height prism

Using the numbers you gave: 
base1 = 7     base2 = 5     h = 4     height prism = 8

Putting this into the equation:  V=(1/2 * (7 + 5) * 4) * 8
V= (1/2 * 12 * 4) * 8
V = 24 * 8
V = 192

The volume of the gift box is 191 inches squared.