a cistern is filled by pipe a in 8 hours and the full cistern can be leaked out by an exhaust pipe b in 12 hours . if both the pipes are opened , in what time the cistern is full ?
time taken to full the cistern = ( 1 / 8 - 1 / 12 ) hrs = 1 / 24 = 24 hrs answer : a
divide(const_1, subtract(divide(const_1, 8), divide(const_1, 12)))