Question 757961
John takes 1/6 hour to do a job
Thomas takes 1/9 hour to do a job
    1/6 + 1/9 = 1/x
Denominator = 54x
    9x + 6x = 54
       15x  = 54
         x  = 54/15
         x  = 3.6hours
         x  = 3hours 36mins.
Hope this helps.
:-)