Question

Length of a rectangle is four times its width. If the perimeter is 100 m, what is the area in square cm?

Answer 1

Set the width to be x. Thus, the length is 4x.

The perimeter is 2(x+4x)=100, so x=10.

Plugging in x=10, you get that 4x=40.

So, the area of the rectangle is 400 $m^2$.

Because there are 100 centimeters in a meter and you are asking for area, you must multiply by $100^2$ to get 4000000 $cm^2$.