Guys, please help me with this homework.

The answer is -4.
You can break the problem up to make it easier to solve,
So 7(x)^3
You would substitute x with -1, due to order of operations, you would find out what is -1 * -1 * -1 is.... the answer would be -1, so 7* -1 is -7.
Now 5(x)^2
Is the same thing 5(-1)(-1) which is 5.
Now combine all the answers so:
-7 + 5 - 2.....
The answer would be -4.