42

Because "9-3" is in parenthesis, that operation is performed before the multiplication.

-12

Order of operation performs multiplication before division, therefore we evaluate 9-21 to get a -12.

8

Division before addition:  4+4=8

6

Parenthesis before division.

This can also be can be symbolized with a vertical alignment of the numerator and denominator.

0

Order of operation will perform the mathematical argument in the "inner" grouping sets. 

(5-2) =3

[3-3]=0

0*2=0

Thats my "final answer"

2

Inside the brackets since subtaction/addition are performed left to right, we have

3-5+3=1

1*2=2

-6

Order of operation would simplify parenthesis first.  We take (3-5)

to give us

-2-2*2

Order of operation would then multiply 2*2 to give us -2-4 to give us -6