Part of tank filled by first tap in 1 h = \( \Large \frac{1}{3} \)

Part of tank filled by second tap in 1 h = \( \Large \frac{1}{4} \)

Part of tank emptied by third tap in 1 h = \( \Large \frac{1}{5} \)

Part of the tank filled by all pipes opened simultaneously in 1 h

= \( \Large \frac{1}{3} \) + \( \Large \frac{1}{4} \) - \( \Large \frac{1}{5} \)

= \( \Large \frac{20+15-12}{60} \) = \( \Large \frac{23}{60}\)

Time taken by all the taps to fill the tank when it is empty

= \( \Large \frac{60}{23} \)h = \( \Large 2\frac{14}{23} \) h