Question

If the length and breadth of a rectangle are doubled, how many times the perimeter of the old rectangle will that of the new rectangle?

Answer 1

new rectangle will be twice of old rectangle
perimeter of old rectangle = 2 (l+b)
perimeter of new rectangle is 2×(2l+2b)=4 (l+b)
hence on comparing them new one is twice

Answer 2

perimeter of old rectangle =2(l+b)
perimeter of new rectangle=4(l+b)
new perimeter-old perimeter=4(l+b)-2(l+b)
(l+b)2
so the change is of 2 times