The perimeter of the rectangle is 126dm. Find the area of a rectangle if its side lengths are 3: 4.

1. Let’s denote by x the large side (length) of the rectangle.

2. Find the smaller side (width) of the rectangle.

3/4 x dm.

3. Find the perimeter of the rectangle.

(x + 3 / 4x) * 2 = 3.5x dm.

4. Let’s compose and solve the equation.

3.5x = 126;

x = 126: 3.5;

x = 36.

5. The large side of the rectangle is x = 36 dm.

6. Find the smaller side of the rectangle.

36 dm * 3/4 = 27 dm.

7. Let’s calculate the area of the rectangle.

36 dm * 27 dm = 972 dm ^ 2.

Answer. The area of the rectangle is 972 square decimeters.