Question

27. If the length and the breadth of a room are
increased by 1 metre, the area is increased by
21 square metres. If the length is increased by
1 metre and breadth is decreased by 1 metre the
area is decreased by 5 square metres. Find the
perimeter of the room.​

Answer 1

40m

let the length and breadth of room be l and b respectively

area of room=lb

after increasing length by 1m=(l+1)

after increasing breadth by 1m=(b+1)

now, according to the question,

(l+1)(b+1)=lb+21

(l+1)(b+1)−lb=21

l+b=20⟶(1)

When, length increased by 1m and breadth is decreased by 1m, then

lb−[(l+1)(b−1)]=5

l−b=6⟶(2)

solving (1) & (2), we get

l=13 and b=7

∴ perimeter=2(l+b)m=2(13+7)=40m

Step-by-step explanation:

I hope its help to you

Answer 2

Answer:

l=12, b=8

perimeter =40