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perimeter(p) = 2l + 2b = 2(l+b)
Let the width be = x cm
So length = x + 5 cms.
By applying the above formula,
40 cms = 2(x+x+5)
20 cms = x+x+5 = 2x+5
2x = 20-5 = 15
x =

= 7.5 cms.
So width = 7.5 cms.; length = 7.5+5 = 12.5 cms. Ans.