Answer:
Infinite solutions
Explanation:
So if simplified it would be
-3x+15=15-3x
Which is basically the same thing if arranged
15-3x=15-3x
-3x+15 can also be 15-3x still the same thing as adding 15 to -3x
So since these are equal anything could be used
like try 0
Both get 15
Try 1
Both get 12
Try legit any number
youll get the same results (I would choose 3 positive easy ones, 0,1,2 and 3 negative ones -1,-2,-3)