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

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 its length is 20 cm?

First, let’s find the area of the square:
S = a2 = 10 ^ 2 = 100 cm2.
The area of the rectangle is 3 times larger:
S = 100 * 3 = 300 cm2.
Formula for the area of a rectangle:
S = ab, where a is the length, b is the width of the rectangle.
Knowing the area and length, we find the width of the rectangle:
b = S / a = 300/20 = 15 cm.
Answer: The width of the rectangle is 15 cm.