Finding the area of a rectangle but only given the perimeter

Question

The perimeter of the rectangle is 40cm but the length of the rectangle is 6cm longer than its width. Whats the area?

Answer 1

Let x = the width

Let x + 6 = the length

P =2l + 2w

40 = 2(x + 6) + 2x

40 = 2x + 12 + 2x

28 = 4x

7 cm = x

length: x + 6 = 7 + 6 = 13

 

A = lw

A = 13(6)

A = 78 cm²