- 5x(x - y) - (y - x) = (x - y)(5x + 1)
- 5x(x - y) - (y - x) = 5x(x - y)
- 5x(x - y) - (y - x) = (x - y)(5x - 1)
- 5x(x - y) - (y - x) = (x + y)(5x - 1)