The shorter side of a rectangle is 20 m. Decreasing the longer side by 30 cm reduces the perimeter by one half. How long are the longer sides of the original rectangle? Explain the reasoning.

3 answers

Let S = shorter side, L = longer side and P = perimeter (all in meters).

2S + 2L = P ---> 40 + 2L = P

2S + 2(L - .3) = P/2 ---> 40 + 2(L - .3) = P/2

Substitute the value for P from the first equation into the second. Solve for L.

I hope this helps. Thanks for asking.
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