Please help me. this is my last problem and i’m clueless.

-3

Step-by-step explanation:

so you SUBSTITUTE -2 in for z

ok i think they are trying to be tricky here

so

-1 - (-(-2))

inside parentheses, the two negatives are going to cancel eachother out.

now you have

-1 - (2)

which is

-1 - 2

-1 minus 2 is -3

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.