The area of a rectangle is 3 times the area of a square with a side of 10 cm. What is the width of a rectangle

The area of a rectangle is 3 times the area of a square with a side of 10 cm. What is the width of a rectangle if it is 20 cm long?

1) Calculate the area of the square using the formula: S = a² = 10² = 100 (cm²);

2) Find out what the area of the rectangle is equal to: 100 · 3 = 300 (cm²);

3) Find the width of this rectangle: a = S: b = 300: 20 = 15 (cm).

Answer: The width of the rectangle is 15 cm.