pipes a and b can fill a tank in 6 and 4 hours . pipe c can empty it in 12 hours . if all pipes are opened together , then the tank will be filled in ?
net part filled in 1 hour = 1 / 6 + 1 / 4 - 1 / 12 = 1 / 3 the tank will be full in 3 hr answer is a
inverse(subtract(add(divide(const_1, 6), divide(const_1, 4)), divide(const_1, 12)))