Answer:
-3x
Explanation:
The order of where the terms are placed definitely matter for subtraction. 5x-2x is 3x, but because the smaller number is first, we've gone into the negatives. Think of it like this:
2x - 5x
-2x -2x
__ __
0 -3x
Because we still have the - in front of the 3, it is a negative 3.
Hope this helps!