You will need the formula for finding the volume of a rectangular prism (cuboid).
V = l x w x h
1. V = x^2 x h
2. To solve for x, you will substitute in the information you know.
150 = x^2 x 24
Divide both sides by 24 to get
6.25= x^2
The square root of 6.25 is 2.5.
x = 2.5 cm