SOLUTION: The perimeter of a rectangle is 30m more than three times it's width. If the perimeter is 84m, find the length and width of the rectangle. (Hint: w= 18m)

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Question 1169123: The perimeter of a rectangle is 30m more than three times it's width. If the perimeter is 84m, find the length and width of the rectangle. (Hint: w= 18m)
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

let the length be l and the width w
the perimeter of a rectangle is P=2%28l%2Bw%29
if the perimeter of a rectangle is 30m more than three times it's width, we have
P=3w%2B30m
If the perimeter is 84m, then
84m=3w%2B30m
84m-30m=3w
54m=3w
w=54m%2F3
w=18m
P=2%28l%2Bw%29......substitute known variables
84m=2%28l%2B18m%29
84m%2F2=l%2B18m
42m=l%2B18m
l=42m-18m
l=24m
so, the length is 24m and the width is 18m