Question 631663
let length be l & width be w

2(l+w)= 80 perimeter

l+w = 40 

new length = (l-2)
new width = (w+2)

New area - old area = 36

(l-2)(w+2)-lw=36
lw+2l-2w-4-lw=36
2l-2w=40
/2
l-w=20
l+w=40

add both equations
2l=60
l=30
so w=10

The dimensions of rectangle are 30 & 10 m