The perimeter of the rectangle is 6.4 cm. Find its sides if one of them is 3 times larger than the other.

In order to find the lengths of the sides of a rectangle, we will compose and solve a linear equation.

To compose the equation, we will apply the formula to find the perimeter of a rectangle.

Let’s remember the formula:

P = 2 (a + b);

It is known that the perimeter of a rectangle is 6.4 cm. It is also known that one of the sides is 3 times larger than the other.

Let’s denote by x cm the length of one of the sides and 3x cm the length of the other side.

2 (x + 3x) = 6.4;

x + 3x = 6.4: 2;

x (1 + 3) = 3.2;

4x = 3.2;

x = 3.2: 4;

x = 0.8 cm is the length of one side and 0.8 * 3 = 2.4 cm is the length of the second side.