Question no.45. explain step by step on pen and paper.



Dear Student,

Let the length and breadth of the room be x and y respectively.Area of room = Length × Breadth = xyAccoring to the question:(x+1)(y+1) - xy = 21xy + x + y + 1 - xy = 21x+y = 21 - 1x+y = 20                                 ...(1)and xy - (x+1)(y-1)  = 5 xy - (xy - x + y - 1) = 5xy-xy+x-y+1 = 5x-y = 5-1x-y = 4                                        ...(2)Adding (1) and (2)2x = 24x=242x= 12 cmSubstituting x = 12 in (1)x+y = 2012 + y = 20y = 20-12y=8 cmPerimeter of room = 2(Length+Breadth) = 2(x+y) = 2(12+8) = 2 × 20 = 40 cm2

Regards
 

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