Question

please explain the solution to attached

Answer 1

i think its 3 hours.
work/time(together)=work/time(rick)
since they're both completing the same amount of work i would set work equal to 1.
it takes both of them 6 hours to the the job so i set one side of the equal to 1/6 then the right side 1/(x+9) because it take rick 9 more hours to complete the job. the next step is to cross multiply and we get 6=x+9 then we just subtract nine to isolate the variable . so then we get 3 hours as a result.