SOLUTION: The length of a rectangle is 2 1/2 times its width. Its area is 90 squares units. What are its dimensions?

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Question 660866: The length of a rectangle is 2 1/2 times its width. Its area is 90 squares units. What are its dimensions?
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
a= lw = 90
l=2 1/2(w)
Substitute l into the first equation
(2 1/2(w))w = 90
2.52w^2 - 90 = 0
Multiples of 90: 30,3: 15,6
Using 15,6 as 2.5 times one of them must equal the other
(2.5w+15)(w-6)=0
w = -15/2.5 NO
w = 6
l = 2 1/2(6) = 15