Order of operations! studying for finals

12 - 2³ -4

1) 2³ =2*2*2=8

2) 12- 8 -4= 4 - 4 =0

12 - 2³ -4=0

PEMDAS 
(parenthesis, exponents, multiplication, division, addition, and subtraction).

So, the first thing you'd do is evaluate the exponent, since there's no parenthesis. So, it would turn to

12-8-4                     (2^3 = 2 * 2 * 2)

The next would be subtraction, since there's no multiplication, division, nor addition. Since there's only multiplication, it doesn't matter which one you do fist. So, it turns to 

12-8-4
4-4
0

So, the answer would be 0.

P.S. Remember PEMDAS, it's awesome ;)