Two pipes can separately fill a tank in 20 and 30 hours respectively. Both the pipes are opened to fill the tank but when the tank is full, 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?
Select the correct option
A) 18 hrs B) 16 hrs C) 15 hrs D) 12 hrs E) 10 hrs
Explanation:   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   ANSWER IS 16 hrs
<result>B</result>
Two pipes can separately fill a tank in 20 and 30 hours respectively. Both the pipes are opened to fill the tank but when the tank is full, 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?