I need to understand how to solve this problem with the best detailed answer please.

Related Rates with the graph

The Lantern Problem: A 60 foot rope is looped through a pulley 36 feet above the ground. A lantern is attached to one end. The other end is held by a man 6 feet tall. The man starts walking away from the point on the ground directly beneath the pulley (and the lantern) at a rate of 5 feet per second (fps) He is holding the rope head high. When the man is 40 feet away from the point on the ground directly beneath the pulley, what is the rate of change of the length of the shadow cast by the man by the lantern