Question 1108166
Bob, y hours for 1 job
Amy, (4/3)y hours for 1 job


{{{1/((4/3)y)+1/y=1/12}}}

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{{{3/(4y)+1/y=1/12}}}


{{{12y(3/(4y)+1/y)=12y/12}}}


{{{9+12=y}}}


{{{highlight(y=21)}}}---------Bob does 1 job in 12 hours, alone.


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{{{(4/3)*21}}}

{{{highlight(28)}}}----------Amy can do 1 job alone in 28 hours.