(-3xy2z0)3

First decide whether the answer is going to be positive or negative
by this rule:

NEGATIVEEVEN=POSITIVE and NEGATIVEODD=NEGATIVE

Yours is NEGATIVEODD, because the exponent 3 is odd, so the
answer will be negative, so bring the negative sign out in front.


-(3xy2z0)3 

Now make sure every factor inside the parentheses shows an exponent.
If it doesn't have one give it a 1 exponent:

-(31x1y2z0)3

Now we remove the parentheses by multiplying every exponent inside
the parentheses by the exponent outside the parentheses, which is 3.

-33x3y6z0

Next change 33 to 3·3·3 or 27, and erase the z0
since it's just 1. 

-27x3y6

Edwin