Answer :

The answer would be -2x + 8.

3 - x - (x - 5)

3 - x - x + 5

3 + (-x - x) + 5

3 - 2x + 5

(-2x + 8).
(-x+3) - (x-5)
-x+3-x+5  (subtraction sign changes all signs within the parentheses)
-2x + 8 (combine variables and constants)