Answer:
It depends
Explanation:
Well you almost got it correct! You made a slight error when distributing the -5,

So you're equation would actually be:

This simplifies to:

I also just realized, you made another slight error when adding -18 and -10, you for some reason got 18? I'm not quite sure what you were trying to do their, by in adding negative number to a negative number, it becomes smaller.
So we have the equation:

I'm not quite sure by what you mean "if the answer is positive or negative"? If you mean the entire value, then there isn't an answer.
The "x" is a variable, so it is an unknown value, it's value varies. Thus we cannot further evaluate the expression x-28.
For example if we plug in 28 as x, the value is neither positive or negative
IF we plug in 2 as x, the value is negative
If we plug in 60, the value is positive.