Answer: y = 6
The triangle has a base of y and a height of 5. The area of the triangle is
area = (1/2)*base*height = 0.5*y*5 = 2.5y
which multiplies with the prism's depth 8 to get 2.5y*8 = 20y
The expression 20y represents the volume of the prism, which we are told is 120 cubic meters, so 20y = 120 solves to y = 6 after dividing both sides by 20.
