Question

The breadth of a rectangle is 4 units less than its length. If the perimeter of the rectangle is 20 units, write a pair of linear equations to model the above situation, assuming the length to be l units and the breadth to be b units.

Answer 1

L=7 units and B=3 units

Explanation:

L=B+4 ... Equation 1

P = 20

P=2(B+L)... Equation 2

20=2(B+B+4)... Substituting equation 1 to equation 2

20=2(2B+4)

20=4B+8

20-8=4B

12=4B

12/4=4B/4

B=3... Solve for B

L=B+4

L=3+4

L=7... Solve for L