the length of a rectangle is increased by 60 and the width..., Percentage, General Mathematics

Question:The length of a rectangle is increased by `60%` and the width is decreased by `20%`. The area decreases by :

A `37 1/2%` 
B `60%` 
C `75%` 
D None

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+ AnswerA

+ ExplanationLet length = l and breadth = b

Let the required decrease in breadth be x%.

Then,`160/100 l xx ((100 - x))/100 xx b`

`= lb => 160 (100 - x)`

`= 100 xx 100`

`or 100 - x`

`= 10000/160`

`= 125/2 => x`

`= (100 - 125/2)`

`= 37 1/2.`

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