a + a - 10 - 12 - a = a + a - a - 10 - 12 = 2a - 22
6x - 8 - 5x - 4 + 9x = 6x - 5x + 9x - 8 - 4 = 10x - 12
a + a - 10 - 12 - a = a + a - a - 10 - 12 = 2a - 22
6x - 8 - 5x - 4 + 9x = 6x - 5x + 9x - 8 - 4 = 10x - 12