HELP!!!!!!!!!!!!!!!! IF SOMEONE GIVES A BS ANSWER I WILL REPORT YOU!!!
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Answer:
12. 3x(x+12), 3x^2+36x
13. 5a(a+8), 5a^2+40a
14. 4x+28
15. 7x-21
16. -2x-8
17. 3x+27
18. 4a-4
19. 3m+6
20. -4a+16
21. 2a-24