-3ac +3cd -8
1) In this expression,
Зас - 9cd - бас +12cd - 8 Combining like terms
-3ac +3cd -8
We might factor out (optionally)
3(cd -ac) -8
Since we can't go further, then we can either leave 3ac +3cd -8 or 3(cd -ac) -8 both expressions are equivalent.
But let's keep it with -3ac +3cd -8 that is the answer.