The area of the rectangle is three times the area of the square. The length of the rectangle is 21 cm.

The area of the rectangle is three times the area of the square. The length of the rectangle is 21 cm. Find the width of the rectangle if the side of the square is 7 cm.

Area of a square formula:
S = a ^ 2, where a is the side of the square.
1) Find the area of the square:
7 ^ 2 = 7 * 7 = 49 (cm ^ 2) – the area of the square.
2) Determine the area of the rectangle:
49 * 3 = 147 (cm ^ 2) – the area of the rectangle.
3) Find out the width of the rectangle. To do this, divide the area of the rectangle by its length:
147: 21 = 7 (cm) – width.
Answer: The width of the rectangle is 7 cm.