A pipe takes a hours to fill the tank. But because of a leakage it took 7 times of its original time. Find the time taken by the leakage to empty the tank  Choose the correct answer
A) 50 min B) 60 min C) 90 min D) 80 min E) 70 min

Rationale: pipe a can do a work 60 min . lets leakage time is x ; then 1 / 60 - 1 / x = 1 / 420 x = 70 min answer : e
Answer: E