How to find the depth of a rectangular prism? ? i already have the length, width ad the volume. but i'm confused on how to find the height?

You have everything you need to find it.
Look at this for a second:

Volume = (length) x (width) x (height)

Divide each side of this equation by (length) x (width), and you have

Height = (Volume) / (length x width)

You have all the numbers on the right side, so you can easily find the height.