i have 2 questions im stuck on what is 5-2{4-(3y-4)} and then what is (x^-9)^6

For the first one, I will start you off.

5-2{4-(3y-4)}
PEMDAS is the order of operations. You cannot simplify anything in the inner most parentheses, but you can for the curly braces. In essence, you distribute the implicit negative one across the terms in the parentheses.
5 - 2{4 - (3y - 4)}
5 - 2{4 + -1(3y - 4)}
5 - 2{4 - 3y + 4}
Next, restate that so that.
5 + -2{4 - 3y + 4}
Now distribute the -2, and finally, combine like terms.

For the second one, just use the rule:
(x^a)^b = x^(ab)