A 26 foot ladder is placed againts a wall.If the top of the ladder is sliding down at a rate of 2 feet per second,then estimate the rate at which the bottom of the ladder is moving away from the wall when the bottom of the ladder is 10feet away from the wall.

Let height and base be h and b respectively.All I could understand was that we have to find db/dt,we are given dh/dt ..can somebody help me with this question?