Math CentralQuandaries & Queries


Question from marylyne, a student:

the perimeter of the rectangular is 70 meters. if the width is 40% of the length, find the dimensions?


Suppose the length is L meters and the width is W meters.


The perimeter is then L + W + L + W = 2L + 2W meters.

Since W is 40% of L, W = 0.40 × L.

Hence you have three facts.

  • The perimeter is 70 meters.

  • The perimeter is 2L + 2W meters.

  • W = 0.40 × L.

Put these three facts together to form an equation in the variable L. Solve this equation for L.


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