If the length and breadth of a rectangular room are each increased by 1 m, then the area of floor is increased by 21 sq. m. If he length is increased by 1 m and breadth is decreased by 1m, then the area is decreased by 5 sq.m. . The perimeter of he floor is :
Let length = `x` metres and breadth = y metres, Then
`(x + 1) ( y + 1) - xy = 21`
`rArr x + y = 20 .`....................................(i)
and , xy -[x + 1) ( y - 1)] = 5`
`hArr x - y = 6 .........................................(ii)
Solving (i) and (ii) , we get ` x= 13 and y = 7`
so, length = 13 m. and breadth = 7 m.
`:.` perimeter = [2 (13 + 7)] m = 40 m.
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