document.write( "Question 441844: a roofer spends 12 hours to shingle a roof alone. The roofer quits after 3 hours and the helper spends another 12 hours to finish. how long would it take the helper alone to do the whole job?\r
\n" ); document.write( "\n" ); document.write( "Work Attempted:
\n" ); document.write( "12/3=(12+x)/15
\n" ); document.write( "I have tried a few different ways and keep coming back to an answer of 60 hours; I am not comfortable with this answer. \n" ); document.write( "
Algebra.Com's Answer #304860 by nerdybill(7384)\"\" \"About 
You can put this solution on YOUR website!
a roofer spends 12 hours to shingle a roof alone. The roofer quits after 3 hours and the helper spends another 12 hours to finish. how long would it take the helper alone to do the whole job?
\n" ); document.write( ".
\n" ); document.write( "Let x = time (hours) it takes for helper working alone
\n" ); document.write( ".
\n" ); document.write( "roofer:
\n" ); document.write( "1 roof per 12 hours
\n" ); document.write( ".
\n" ); document.write( "helper
\n" ); document.write( "1 roof per x hours
\n" ); document.write( ".
\n" ); document.write( "3(1/12) + 12(1/x) = 1
\n" ); document.write( "multiplying both sides by 12x:
\n" ); document.write( "3(x) + 12(12) = 12x
\n" ); document.write( "3x + 144 = 12x
\n" ); document.write( "144 = 9x
\n" ); document.write( "16 hours = x\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );