2 pipes can separately fill a tank in 20hrs and 30hrs respectively. Both the pipes are opened tofill the tank, a leak develops in the tank through which one-third of water supplied by both the pipes goes out. What is the total time taken to fill the tank? Answers.
A) 12 hrs B) 14 hrs C) 16 hrs D) 18 hrs E) 20 hrs
1/20 + 1/30 = 1/12   1 + 1/3 = 4/3   1 --- 12   4/3 --- ?     4/3 * 12= 
<gadget id="calculator">  4/3 * 12</gadget>
<output>16</output>
16 hrs   16 hrs
<result>C</result>
2 pipes can separately fill a tank in 20hrs and 30hrs respectively. Both the pipes are opened tofill the tank, a leak develops in the tank through which one-third of water supplied by both the pipes goes out. What is the total time taken to fill the tank?