Given:
Sheila - 5 feet off the ground, 3 feet horizontally form the base of the ladder.
ladder - 15 feet from the wall.
Find how high up the wall the top of the ladder is.
5 : 3 = x : 15
5*15 = 3x
75 = 3x
75/3 = 3x/3
25 = x
The top of the ladder is 25 feet high.