Rob's backyard measures 30 feet by 20 feet. She wants to install a border of grass around the perimeter that is all the same size and then install in the center a stone patio that measures 400 square feet. how wide should the grass perimeter be?
thanks!
Aggie
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1st figure out the total area of the yard 30*20 = 600
2nd figure out the area of the grass perimeter = 600 - 400 = 200
3rd set variable "x" to equal the width of the perimeter
4th set up equations
for each 30 ft length the area of the perimeter will be 30x
for each 20 ft lenfth (first we have to subtract x from each side)
(20-2x)x
the total area of the perimeter = 200 = 2*30x+2*(20-2x)x
and solve for x
Anonymous
(30-x)(20-x) = 400
600 - 50x + x^2 = 400
x^2-50x +200=0
Use quad formula