The angle of the water slide is 60 degrees.
The equation that models his work is 3 × 20 = 60 degrees.
<h3>How to find the sum of angles of a figure/object?</h3>
He wants to measure the angle of a water slide at the lake.
He used a sheet of folded paper that formed 20 degrees to measure the angle of the the water slide at the lake.
He noticed three folded paper angle fits in the angle made by the slide and the ground.
Since each angle is equals to 20 degrees, and the three fits into the angle made by the slide and the ground, the angle of the water slide is as follows:
20 × 3 = 60 degrees
learn more on angles here: brainly.com/question/16746032