SOLUTION: a rectangular garden is 30 feet by 40 feet long.A walk of uniform with that surrounds it has an area of 280 square feet.Find the width of the walk

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Question 978889: a rectangular garden is 30 feet by 40 feet long.A walk of uniform with that surrounds it has an area of 280 square feet.Find the width of the walk
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x, width
y, length
u, uniform width of the walk path around the rectangular garden
A, the area of the walk path around the garden
-
u is unknown
y=30
x=40
A=280

Garden area, xy
Combined walkway and garden area, %28x%2B2u%29%28y%2B2u%29
Walkway area only, highlight_green%28%28x%2B2u%29%28y%2B2u%29-xy=A%29

"Find the width of the walk."
The only unknown variable in the green-outlined equation is u. That is what the question
asks to find. Work with THAT equation to solve for u. Try to go as far as possible completely
in symbols before subsituting the given values.


---partway through the process,
2uy%2B2xu%2B4u%5E2-A=0
4u%5E2%2B%282x%2B2y%29u-A=0