A 25-foot ladder is leaning against a house (see figure). The base of the ladder is pulled away from the house at a rate of 2 feet per second. How fast (in ft/sec) is the top of the ladder moving down the wall when the base is 7 feet, 15 feet, and 20 feet away from the house?

A ladder is shown leaning against the right side of a house.
The ladder is labeled 25 ft.
An arrow labeled r points away from the top of the ladder and straight down towards the ground.
Another arrow labeled 2 ft/sec points away from the bottom of the ladder in a direction parallel to the ground and away from the house.
(a)
7 feet away from the house
ft/sec
(b)
15 feet away from the house
ft/sec
(c)
20 feet away from the house
ft/sec