Question

if the length of the rectangle is increased by 8 metre its area increases by 72 sq.m. the breadth of the rectangle is

Answer 1

let the breadth be b
let the length be l
area = l ×b

new length = l+8
new area = lb +72sq.m
so,
(l+8)×b = lb+72
lb+8b =lb+ 72
on cancelling lb on both the sides,
8b=72
b=9

Answer 2

Let the b = breadth, l = length and area = lb.

length = l+8 and area = lb +72sq.m.

Breadth of the rectangle =  (l+8)×b = lb+72 => lb+8b =lb+ 72.

You can cancel the lb on both sides 8b=72 => b=9.

The breadth of the rectangle = 9.