Explanation:
3 log₆9 + log₆12 + log₆64 - log₆72
= log₆9³ + log₆12 + log₆64 - log₆72
log₆729 + log₆12 + log₆64 - log₆72
log₆(729 x 12 x 64) = log₆776
= log₆6₅ = 5 log₆6 = 5
N.B: log₆6 = 1