Taps A and B can fill a tank in 15 minutes and 10 minutes, respectively while tap C can empty the full tank in x minutes. If all the three taps are opened together, the tank is filled completely in 8 minutes. Tap C alone will empty $\frac{3}{8}$th part of the tank in:

9 minutes

A+ = 15 min, B+ = 10 min, A + B + C = 8 min,

⇒ A + B + C = 15,  (Efficiency)

⇒ 8 + 12 + C = 15,

⇒ 20 + C = 15,

⇒ C = -5,

⇒ \(\frac{3}{8}\) of total capacity = \(\frac{3}{8}\) x 120 = 45 units,

⇒ Time required by C to empty 45 units of the total tank = \(\frac{45}{5}\) = 9 minutes.