document.write( "Question 1174768: Jeff and Kirk can build a​ 75-ft retaining wall together in 4 hours. Because Jeff has more​ experience, he could build the wall by himself 2 hours quicker than Kirk. How long would it take Kirk​ (to the nearest​ minute) to build the wall by​ himself? \n" ); document.write( "
Algebra.Com's Answer #800252 by ankor@dixie-net.com(22740)\"\" \"About 
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Jeff and Kirk can build a​ 75-ft retaining wall together in 4 hours.
\n" ); document.write( " Because Jeff has more​ experience, he could build the wall by himself 2 hours quicker than Kirk.
\n" ); document.write( "How long would it take Kirk​ (to the nearest​ minute) to build the wall by​ himself?
\n" ); document.write( ":
\n" ); document.write( "the length of the wall is not relevant in this problem
\n" ); document.write( ":
\n" ); document.write( "let t = time required by Kirk to build the wall by himself
\n" ); document.write( "Jeff takes 2 hrs less, therefore
\n" ); document.write( "(t-2) = time required by Jeff
\n" ); document.write( "let the completed job = 1
\n" ); document.write( ":
\n" ); document.write( "\"4%2Ft\" + \"4%2F%28%28t-2%29%29\" = 1
\n" ); document.write( "multiply eq by t(t-2), cancel the denominators
\n" ); document.write( "4(t-2) + 4t = t(t-2)
\n" ); document.write( "4t - 8 + 4t = t^2 - 2t
\n" ); document.write( "8t - 8 = t^2 - 2t
\n" ); document.write( "arrange as a quadratic equation on the right
\n" ); document.write( "0 = t^2 - 2t - 8t + 8
\n" ); document.write( "0 = t^2 - 10t + 8
\n" ); document.write( "using the quadratic formula, a=1; b=-10, c=8, the positive solution
\n" ); document.write( "t = 9.1231 hrs
\n" ); document.write( "which is 9 + .1231(60) 9 hrs 7 min is time required by Kirk alone \n" ); document.write( "
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