Find the sides of a rectangle if one side is 3 times smaller than the other, and the rectangle has a perimeter of 40.

1. Let’s denote the length of the shorter side of the rectangle through x.

2. Determine the length of the larger side of the rectangle:

3 * x = 3x cm.

3. Let’s compose and solve the equation:

(3x + x) * 2 = 40;

4x * 2 = 40;

8x = 40;

x = 40: 8;

x = 5.

4. The length of the smaller side of the rectangle is x = 5 cm.

5. What is the length of the longer side of the rectangle?

3 * x = 3 * 5 = 15 cm.

Answer: the sides of the rectangle are 5 cm; 15 cm; 5 cm; 15 cm.