document.write( "Question 1142603: Two college students have started their own business building computers from kits. Working alone, one student can build a computer in 20 hours. When the second student helps, they can build a computer in 7.5 hours. How long would it take the second student, working alone to build the computer? create and equation and solve \n" ); document.write( "

Algebra.Com's Answer #763296 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

You can put this solution on YOUR website!
Two college students have started their own business building computers from kits.
\n" ); document.write( " Working alone, one student can build a computer in 20 hours.
\n" ); document.write( " When the second student helps, they can build a computer in 7.5 hours.
\n" ); document.write( " How long would it take the second student, working alone to build the computer?
\n" ); document.write( " create and equation and solve
\n" ); document.write( ":
\n" ); document.write( "let x = the time required by the 2nd student alone
\n" ); document.write( "let the completed job = 1
\n" ); document.write( ":
\n" ); document.write( "Each will do a fraction of the job, the two fractions add up to 1
\n" ); document.write( " $\"7.5%2F20\"$ + $\"7.5%2Fx\"$ = 1
\n" ); document.write( "multiply by 20x, cancel the denominators
\n" ); document.write( "7.5x + 20(7.5) = 20x
\n" ); document.write( "7.5x + 150 = 20x
\n" ); document.write( "150 = 20x - 7.5x
\n" ); document.write( "150 = 12.5x
\n" ); document.write( "x = 150/12.5
\n" ); document.write( "x = 12 hrs required by the 2nd student alone
\n" ); document.write( " \n" ); document.write( "

\n" );