Question 754822
Tina's rate = 1/8 job/hr
Tom's rate = 1/4 job/hr
Together the rate is 1/x job/hr
Equation: rate + rate = together rate
            1/8 + 1/4 = 1/x
        Common denominator = 8x
             x + 2x = 8
                3x  =  8
                 x  =  8/3 or 2 2/3 hrs
  Therefore they can do the job together in
   2 hours 40 minutes.
Hope this helps
:-)