Problem Solving

Pumps A, B, and C operate at their respective constant rates. Pumps A and B, operating simultaneously, can fill a certain takn in 6/5 hours; pumps A and C, operating simultaneously, can fill the tank in 3/2 hours; and pumps B and C, operating simultaneously, can fill the tank in 2 hours. How many hours does it take pumps A, B, and C, operating simultaneously, to fill the tank?

(A) 1/3
(B) 1/2
(C) 2/3
(D) 5/6
(E) 1

Any input on the above will be highly appreciated. Thanks in advance.