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A rectangular sandbox is surrounded on all sides by a strip of grass that is 5 feet wide on all sides.
The length of the sandbox is 4 feet more than the width, and the
total area for the sandbox and the grass is 189 square feet. Find the dimensions of the sandbox.
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Let x be the width of the large rectangle, in feet; then its length is (x+4) feet.
The area equation is
x*(x+4) = 189.
It gives
x^2 + 4x - 189 = 0
=
You need the positive root, ONLY : x = 11.892 (approximately).
So, the dimensions of the large rectangle are 11.892 ft and 11.892+4 = 15.892 ft.
The dimensions of the sandbox are 5*2 = 10 ft less than these values.
ANSWER. The dimensions of the sandbox are 11.892 - 10 = 1.892 ft and 15.892 - 10 = 5.892 ft.
Solved.