A pipe can fill a tank in 56 hours, but it takes 16 hours more due to a leak in its bottom. In how much time (in hours) can the leak alone empty $83\frac{1}{3}$% of the tank?

126 210 252 105

210

A+ = 56 hrs, A + B = 72 hrs, ⇒ A + B = 7  (Efficiency) ⇒ 9 + B = 7, ⇒ B = -2, Time required for B to empty 83.33% of tank = 83.33% x 504 = 420 units, ⇒ \(\frac{420}{2}\) = 210 hrs.