Question

The length of a rectangular hall is 3 metres more than it's breadth. If the perimeter is 66 metres, what are it's dimensions?

Answer 1

Let the length and breadth of the hall are l and b respectively. then, l=b+3
then by the given question, 
2(l+b)=66
or, 2(b+3+b)=66
or, 2(2b+3)=66
or, 4b+6=66
or, 4b=66-6=60
or, b=60/4=15 meter
so, l=b+3=15+3=18

Answer 2

let the breadth of the rectangular hall be x.
then the length = x+3
perimeter of a rectangle= 2(l+b)
a/q          2(x+3+x) = 66
           ⇒2(2x+ 3) ==66
           ⇒ 4x + 6 = 66
          ⇒ 4x = 66-6
           ⇒ x = 60/4
          ∴ x = 15
so the breadth of the rectangular hall is 15 metres 
and the length is 15+ 3 = 18 meters.