Piz look at the pic
[tex]piz \: help \:me \: thx[/tex]

Answer:
-12a²+9a-5
Step-by-step explanation:
-7a²+3a-9 - (5a²-6a-4)=
-7a²+3a-9-5a²+6a+4=
-12a²+9a-5