SOLUTION: the length of a rectangular is 3 times its width.it perimeter is 84m.find the length of the rectangular.

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Question 673665: the length of a rectangular is 3 times its width.it perimeter is 84m.find the length of the rectangular.
Answer by rm29924(97) About Me  (Show Source):
You can put this solution on YOUR website!
the formula to find the perimeter of a rectangle is perimeter = 2(length)+2(width)
let width = w
the length is 3 times the width therefore length = 3w
the perimeter is 84m
84=2(3w)+2w
84=6w+2w
84=8w
divide both sides by 8 to get w by itself
10.5=w
the length is 3w so 3(10.5)
answer: the length is 31.5 m
check answer:
84=2(3w)+2w
84=2(3x10.5)+2(10.5)
84=2(31.5)+21
84=63+21
84=84