In a recreation park a children's slide is 27 feet long and makes an able of 39 degrees with the ground. Its top is reached by a ladder 18 feet long. What is the angle of inclination of the ladder.

Each angle on a triangle would add up to 180 degrees. Since a ladder goes straight up, that angle would be 90 degrees. If you add that with the 39 degree angle, you'd get 129. Subtract that from 180 and you have your answer.