Question 851090
Rate of a is 1/x.
Rate of b is 1/y.


{{{R*T=J}}}, uniform rate situation for task or job completion, "work".
Agents working simultaneously do so at a rate the sum of their individual rates.


EQUATIONS FROM THE DESCRIPTION
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{{{(1/x+1/y)*8=1}}}
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{{{(1/x+1/y)*6+(1/y)*6=1}}}


The rest of the solution is not shown, so you can solve the two simultaneous equations.  Very important is to understand the concept of uniform rates, and to analyze the problem and develop the equations shown.