(-18xy) - (-8xy) is equal to:

1. 10xy

2. -10xy

3. 26xy

4. -26xy

(9a + 7b - 6c) - (2a - 3b + 4c) is equal to:

1. 7x + 7b + 10c

2. 7a + 10b - 10c

3. 7a - 10b + 10c

4. 7a - 10b - 10c