Answer 1

\[9a(6a - 5b) - 12 a^2 (6a - 5b)\]
\[ = (9a - 12 a^2 )(6a - 5b) [\text{ Taking }(6a - 5b)\text{ as the common factor }]\]
\[ = 3a(3 - 4a)(6a - 5b) [\text{ Taking 3a as the common factor of the quadratic }(9a - 12 a^2 )]\]