How do I find a missing side of a triangular prism?

Question

So the volume itself is given (that being 8640 meters cubed), i also have the height as 9 meters and the length as 40 meters. How do I find the missing width?

Answer 1

Assuming that the height is the height of the triangle and the length is the base of the triangle...

V=(1/2)(b)(h)(w)

8640=(1/2)(40)(9)(w)

8640=(20)(9)(w)

8640=180*w

w=8640/180

w=48 meters