Question

If the perimeter of a rectangle and a square,each is equal to 80cms,and difference of their area is 100sqcms,sides of the rectangle are

Answer 1

let l,b and a be the sides of the rectangle and square respectively
 then
given,
2(l + b) = 80
⇒ l + b = 40
also, 
4a = 80
⇒ a = 20
also,

a² -lb = 100
⇒ lb = 300
 solving for l, b
l = 30, b = 10

Answer 2

4a=2b+2c=80
b+c=40
a=20cm
a^2-bc=100
400-bc=100
bc=300.
b=30 c =10
where a is side of square
b and c are sides of rectangle