Number of hours Tap A requires to fill an empty tank : 8 hours

Number of hours Tap B requires to empty the full tank : 12 hours

Amount of water filled by Tap A in empty tank in one hour: \(\frac{1}{8}\)

Amount of water Tap B empties in one hour: \(\frac{1}{12}\)

Amount of water filled by Tap A and Tap B together in one hour: \(\frac{1}{8}-\frac{1}{12}=\frac{1}{24}\)

∴ They can fill the tank together in 24 hours.