(1) Subtract the sum of 3a and 4a from 9a
(2) Subtract (β5xy + 9yz) from (3xy β 4yz)
(3) Subtract (7m2 β 2m) from (β4m β 7m2)
(4) Subtract (6a β 4b + c) from (βa + 3b β 5c)
(5) Subtract (β4x β 8y + 7) from (3y β 7x + 1)
(6) How much should be added to (5x β 3y) to get (3x β 5y)?