Answer:
37. B
38. D
39. C
40. A
Step-by-step explanation:
37. 12x - 8y +1 3z
+ -8x + 7y + 6z
= 4x - y + 19z
38. 37mn
+ 13mn
= 50mn
39. 6ab²c - 8abc
+ 13abc
-5ab²c
3ab²c
= 4ab²c + 5abc
40. 8x + 4y + 15
+ -4x + 6y + 8
5x + 4y - 15
10x + 5
= 19x + 14y + 13
