This is the concept of volume of solid figures, the volume of a given figure is given by:
volume=(base area)*(height)
In our case the base area will be given by the area of the trapezoid. Which is:
Area=1/2*h*(a+b)
height,h=x
a=x
b=2x
thus;
Area=1/2*x*(2x+x)=3/2x^2
Given that the height of the prism is 20 units, the volume will be:
V=(3/2 x^2*20)
V=30x^2 cubic units
The answer is 30x^2 cubic units
