document.write( "Question 924413: A alone would take 6 hours more to complete the job than if both A and B would work together. When B worked alone he took 1.5 hours more to complete the job and A and B worked together. How much time they will take if they work together? \n" ); document.write( "
Algebra.Com's Answer #560832 by ankor@dixie-net.com(22740)\"\" \"About 
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A alone would take 6 hours more to complete the job than if both A and B would work together.
\n" ); document.write( " When B worked alone he took 1.5 hours more to complete the job and A and B worked together.
\n" ); document.write( " How much time they will take if they work together?
\n" ); document.write( ":
\n" ); document.write( "let t = time required when A & B work together
\n" ); document.write( "Let the completed job = 1
\n" ); document.write( "\"t%2Fa\" + \"t%2Fb\" = 1
\n" ); document.write( ":
\n" ); document.write( "\" A alone would take 6 hours more to complete the job than if both A and B would work together.
\n" ); document.write( "\"%28%28t%2B6%29%29%2Fa\" = 1
\n" ); document.write( "therefore
\n" ); document.write( "a = t+6
\n" ); document.write( "\" When B worked alone he took 1.5 hours more to complete the job and A and B worked together.\"
\n" ); document.write( "\"%28%28t%2B1.5%29%29%2Fb\" = 1
\n" ); document.write( "therefore
\n" ); document.write( "b = t+1.5
\n" ); document.write( "Replace a & b in the 1st equation
\n" ); document.write( "\"t%2F%28%28t%2B6%29%29\" + \"t%2F%28%28t%2B1.5%29%29\" = 1
\n" ); document.write( "multiply the equation by (t+6)(t+1.5), cancel the denominators, we have:
\n" ); document.write( "t(t+1.5) + t(t+6) = (t+6)(t+1.5)
\n" ); document.write( "t^2 + 1.5t + t^2 + 6t = t^2 + 1.5t + 6t + 9
\n" ); document.write( "2t^2 + 7.5t = t^2 + 7.5t = 9
\n" ); document.write( "2t^2 - t^2 + 7.5t - 7.5t = 9
\n" ); document.write( "t^2 = 9
\n" ); document.write( "t = 3 hrs if they work together?
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "We can check this, now we know that a would take 9 hrs alone and b take 4.5 hr
\n" ); document.write( "\"3%2F9\" + \"3%2F4.5\" = 1
\n" ); document.write( ".333 + .667 = 1
\n" ); document.write( "
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