Question

3a(2a-b)-[a(6a-3b)-b(3a-5b)]

Answer 1

3 a ( 2 a - b ) - [ a ( 6 a - 3 b ) - b ( 3 a - 5 b ) =
6 a ² - 3 a b - [ 6 a ² - 3 a b - 3 a b + 5 b ² ]
6 a ² - 3 a b - 6 a ² + 3 a b +3 a b - 5 b ² =
- 5 b ² + 3 a b