SOLUTION: I am relearning Algebra for the ACT and I'm stuck on this problem. Can you help me? Marlo has a basketball court that measures 30 feet by 50 feet. She needs a grass strip around

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Question 762029: I am relearning Algebra for the ACT and I'm stuck on this problem. Can you help me?
Marlo has a basketball court that measures 30 feet by 50 feet. She needs a grass strip around it. How wide must the strip be, in feet, to provide 900 square feet of grass?
A. 3
B. 4
C. 5
D. 6
E. 7
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Grass strip + the court = 900 sq. ft.
The court by itself is 30%2A50=1500 sq. ft.

The grass strip + the court is some unknown width, w more than the border between grass strip and court. This whole combined area is %2830%2B2w%29%2850%2B2w%29=1500%2B900 sq. ft.

2%2A2%2815%2Bw%29%2825%2Bw%29=2400
%2815%2Bw%29%2825%2Bw%29=600
15%2A25%2B15w%2B25w%2Bw%5E2=600
w%5E2%2B40w%2B375=600
w%5E2%2B40w-225=0
highlight%28%28w%2B45%29%28w-5%29=0%29
One of the solutions will make sense and the other will not make sense.
highlight%28w=5%29 feet.
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