Two pipes working together can fill a fish tank in 12 minutes. If one pipe fills the fish tank 10 minutes faster than the second pipe, in what time the second pipe alone can fill the fish tank?

30 min

Here, we can solve these type of question easily by answer option.

As per question.

Lets assume the time of second pipe is 30 min (as per option 2 for easy calculation), then the time of first pipe will be 30 - 10 = 20 min.

Hence, second pipe can fill the tank in 30 min.