-3a-4b+5
(3a - 6b +12)- (6a - 2b+ 7).
step 1: remove parentheses and change 2b +7 to 2b -7 and 6a -2b to 6a +2b
3a - 6b +12- 6a + 2b- 7
-3a-4b+5
step 2: from 3a - 6b +12- 6a +2b- 7
subtract: 3a - 6a= -3a.
now its -3a - 6b + 12 - 6a + 2b - 7
then 6b - 2= 4
now is -3a - 4b + 12 - 7
then 12 - 7 =5
Answer: -3a-4b+5
sorry is messy
