document.write( "Question 294418: A 50 foot by 60 foot parking lot is torn up to install a sidewalk of uniform width around its perimeter. The new area of the parking lot is three-fourths of the old area. How wide is the sidewalk? \n" ); document.write( "
Algebra.Com's Answer #212328 by ankor@dixie-net.com(22740)\"\" \"About 
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A 50 foot by 60 foot parking lot is torn up to install a sidewalk of uniform width around its perimeter. The new area of the parking lot is three-fourths of the old area. How wide is the sidewalk?
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\n" ); document.write( "Find the original area of the parking lot: 50 * 60 = 3000 sq/ft
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\n" ); document.write( "Find 3/4 of the area: .75(3000) = 2250 sq/ft
\n" ); document.write( ":
\n" ); document.write( "Let x = the width of the sidewalk
\n" ); document.write( ":
\n" ); document.write( "new width*new length = 2250 sq/ft
\n" ); document.write( "(50-2x)*(60-2x) = 2250
\n" ); document.write( "FOIL
\n" ); document.write( "3000 - 100x - 120x + 4x^2 = 2250
\n" ); document.write( "Arrange as a quadratic equation on the left
\n" ); document.write( "4x^2 - 220x + 3000 - 2250 = 0
\n" ); document.write( ":
\n" ); document.write( "4x^2 - 220x + 750 = 0
\n" ); document.write( "Simplify, divide by 2
\n" ); document.write( "2x^2 - 110x + 375 = 0
\n" ); document.write( "Solve using the quadratic formula
\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( "in this problem a=2, b=-110, c=375
\n" ); document.write( "\"x+=+%28-%28-110%29+%2B-+sqrt%28-110%5E2-4%2A2%2A375+%29%29%2F%282%2A2%29+\"
\n" ); document.write( ":
\n" ); document.write( "\"x+=+%28110+%2B-+sqrt%2812100+-+3000+%29%29%2F4+\"
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\n" ); document.write( "I'll let you do the math here, you will get two solutions but only the
\n" ); document.write( "smaller value will be a valid solution (x ~ 3.65 ft)
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\n" ); document.write( "Check it in the original equation
\n" ); document.write( "(50 - 2(3.65)) *(60 - 2(3.65)) = \n" ); document.write( "
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