Pipe A can fill a tank in 5 hours. Due to a leak at the bottom, it takes 10 hours for the pipe A to fill the tank. In what time can the leak alone empty the full tank?  Choose the correct choice from the following
A) 67
B) 10
C) 18
D) 26
E) 12

Rationale: "let the leak can empty the full tank in x hours 1 / 5 - 1 / x = 1 / 10 = > 1 / x = 1 / 5 - 1 / 10 = 1 / 10 = > x = 10 . answer : b"
Answer: B