a cistern which could be filled in 10 hours takes 2 hour more to be filled owing to a leak in its bottom . if the cistern is full , in what time will the leak empty it ?
"let the leak empty the full cistern in x hours 10 x / x - 10 = 10 + 1 x = 110 hours answer is e"
inverse(subtract(divide(const_1, 10), divide(const_1, const_10)))