Question 885275
The rates of each working together are added.  Arrange rates as TASK per HOUR.
Two People, {{{1/7}}}
One person, {{{1/(x+2)}}}
The other person, {{{1/x}}}


{{{highlight_green(1/x+1/(x+2)=1/7)}}}.
Solve for x and you can find the "one person's" rate, OR the time for the task.





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You should find the quadratic equation occurs, {{{x^2-12x-14=0}}}, and the sensible solution which works is {{{x=6+5sqrt(2)}}}.   This is about 13.07 hours.