Question 1195970
j, the time for Jun to do the repair job by himself
(j+2), the time for Ben to do the job by himself


{{{highlight_green(1/j+1/(j+2)=1/3)}}}

{{{3j(j+2)(1/j+1/(j+2))=3j(j+2)(1/3)}}}

{{{3(j+2)+3j=j(j+2)}}}

{{{3j+6+3j=j^2+2j}}}

{{{6j+6=j^2+2j}}}

{{{highlight_green(j^2-4j-6=0)}}}


{{{j=(4+- sqrt(16-4(-6)))/2}}}

{{{j=(4+- sqrt(40))/2}}}

{{{j=(4+- 2*sqrt(10))/2}}}

{{{highlight(j=2+sqrt(10))}}}-----------time in hours for Jun working alone
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{{{highlight(4+sqrt(10))}}}------------time for Ben, working alone