Find the sum or difference.
1. x-2+x+6

2. 2n-4n-3

3. 2(-3y-1)+(2y+7)

4. (6g-9)+1/3(15-9g)

5. (1-3k)-4(2+2.5k)

6. 1/2(2r+4)-1/4(16-8r)

7. You earn (4x+12) points after completing x levels of a video game then lose (2x-5) points. Write an expression that represents the total number of points you have now.

Factor the expression using the GCF.

8. 7+28

9. 25+50

10. 7b-7

11. 8a-16

12. 8x+12

13. 12y+34t

14. 10w+50z

15. 10v+12n

16. 9a+15b

Factor out the coefficent of the variable.

17. 1/2a - 1/2

18. 1/4d - 3/4