If the length and breadth of a rectangular ro | vedclass

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(D) Let the length and breadth of the rectangular room be $l$ and $b$ respectively.According to the first condition:$(l+1)(b+1) - lb = 21$$lb + l + b

Vedclass · Accepted Answer

$40$

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(D) Let the length and breadth of the rectangular room be $l$ and $b$ respectively.According to the first condition:$(l+1)(b+1) - lb = 21$$lb + l + b + 1 - lb = 21$$l + b + 1 = 21$$l + b = 20$ $...(1)$According to the second condition:$(l+1)(b-1) - lb = -5$$lb - l + b - 1 - lb = -5$$-l + b - 1 = -5$$-l + b = -4$$l - b = 4$ $...(2)$Adding equations $(1)$ and $(2)$:$(l + b) + (l - b) = 20 + 4$$2l = 24$$l = 12\, m$Substituting $l = 12$ in equation $(1)$:$12 + b = 20$$b = 8\, m$The perimeter of the floor is given by the formula $P = 2(l + b)$.$P = 2(12 + 8) = 2(20) = 40\, m$.

If the length and breadth of a rectangular room are each increased by $1\, m$,then the area of the floor is increased by $21\, m^2$. If the length is increased by $1\, m$ and the breadth is decreased by $1\, m$,then the area is decreased by $5\, m^2$. The perimeter of the floor is.......$m$.

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