Since it's a one-variable equation, it has only one solution:
25 - 4x = 15 - 3x + 10 - x
25 - 4x + x = 15 - 3x + 10
25 - 3x = 15 - 3x + 10
- 3x = 15 - 3x + 10 - 25
- 3x = 15 - 3x - 15
- 3x + 3x = 15 - 15
0 = 15 - 15
0 = 0
Hope it helped,
BioTeacher101