3/4a
2ab - 3ab + 6ab - 8ab
3c + 2c - 2c(2) + 4c
3/2x
3xy + 4z - 5xy - 7z
1/2x(2) + 3/2x - 1/2x(2)
9c - 2c(2)
- 3ab
-1/2a + 3/4a + 1/2a
-2xy - 3z
