A rectangle has length 72 cm and width 56 cm. A second rectangle has the same area as this one, but its width is 21 cm. What is the length of the second triangle?

Answer 1

The area of the first rectangle is 72 cm x 56 cm = <<72*56=4032>>4032 cm^2.
Let x be the length of the second rectangle.
The area of the second rectangle is x cm x 21 cm = 4032 cm^2.
Thus, x = 4032 cm^2 / 21 cm = 192 cm.
The length of the second rectangle is 192 cm. Answer: \boxed{192}.