Simple maths problem, did I do it right?

I had this problem on a test. I failed it there due to lack of time, but I still want to know if I can solve it. Did I do it right?

Code:

`Pump 1 pumps up the oil in a tank in 24 H. Pump 2 pumps up the oil in 36 H. How many H does it take to pump up the oil if both of the pumps are working?`

/----\

Work

/-------------\

/Capacity|H \

/-----------------\

After 100 units of work, the oil has been pumped up.

Work/Pump1 H = Pymp 1 Capacity

100/24 = 4,167

Work/Pump2 H = Pump 2 Capacity

100/36 = 2,778

Pump 1 Capacity+Pump 2 Capacity

4,167+2,778 = 6,945

Work/Capacity = H

100/6,945 ~= 14,4

4*0,6=2,4

Result: 14 H and 24 min