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A livestock pen is built in the shape of a rectangle that is 2 times as long as it is wide. the perimeter is 42 feet. if the material used to build the pen is $ 1.25 per foot for the longer sides and $ 2.50 per foot for the shorter sides (the shorter sides have gates, which increase the cost per foot), find the cost to build the pen.

Respuesta :

Let width = x ft  then 
2x + 2(2x) = 42
6x = 42
x = 7 

so the width is 7 ft and length is 14 ft.

So the cost to build the pen =  14*1.25 + 14*1,25 + 7*2.50 + 7*2.50
=  70  answer