document.write( "Question 324807: After 5 hours of house painting, Jess asked the assistance of Jon. Together, they finished the job in 4 more hours. Had Jon joined in an hour after Jess started working, the job would have been finished in 7 hours. How long would it have taken Jess to paint the house alone? \n" ); document.write( "
Algebra.Com's Answer #232570 by ankor@dixie-net.com(22740)\"\" \"About 
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After 5 hours of house painting, Jess asked the assistance of Jon.
\n" ); document.write( " Together, they finished the job in 4 more hours.
\n" ); document.write( "Had Jon joined in an hour after Jess started working, the job would have been finished in 7 hours.
\n" ); document.write( " How long would it have taken Jess to paint the house?
\n" ); document.write( ":
\n" ); document.write( "Let x = Jess time painting the house alone
\n" ); document.write( "Let y = Jon's time painting the house
\n" ); document.write( "Let the completed job = 1 (a painted house)
\n" ); document.write( ":
\n" ); document.write( "Write an equation for each scenario
\n" ); document.write( ":
\n" ); document.write( "\"After 5 hours of house painting, Jess asked the assistance of Jon. Together, they finished the job in 4 more hours.\"
\n" ); document.write( "\"9%2Fx\" + \"4%2Fy\" = 1
\n" ); document.write( ":
\n" ); document.write( "\"Had Jon joined in an hour after Jess started working, the job would have been finished in 7 hours.\"
\n" ); document.write( "\"8%2Fx\" + \"7%2Fy\" = 1
\n" ); document.write( ":
\n" ); document.write( "We can combine the two equations
\n" ); document.write( "\"9%2Fx\" + \"4%2Fy\" = \"8%2Fx\" + \"7%2Fy\"
\n" ); document.write( "\"9%2Fx\" - \"8%2Fx\" = \"7%2Fy\" - \"4%2Fy\"
\n" ); document.write( "\"1%2Fx\" = \"3%2Fy\"
\n" ); document.write( "cross multiply
\n" ); document.write( "y = 3x
\n" ); document.write( ":
\n" ); document.write( "Use substitution in the 1st equation
\n" ); document.write( "\"9%2Fx\" + \"4%2F%283x%29\" = 1
\n" ); document.write( "multiply by 3x, results
\n" ); document.write( "3(9) + 4 = 3x
\n" ); document.write( "27 + 4 = 3x
\n" ); document.write( "31 = 3x
\n" ); document.write( "x = \"31%2F3\"
\n" ); document.write( "x = 10.3333 hrs (Jess time alone 10\"1%2F3\" hrs)
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "check solution, find y
\n" ); document.write( "y = 3(10.333)
\n" ); document.write( "y = 31 hrs
\n" ); document.write( ":
\n" ); document.write( "check in the 2nd equation
\n" ); document.write( "\"8%2F10.333\" + \"7%2F31\" =
\n" ); document.write( ".714 + .226 = 1, confirms our solution\r
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