1. 8a+6+4-a. You can combine like terms.
8a-a=7a. 6+4=10
You answer is going to be B, 7a+10.
2. 7b+4-2b-2. Combine like terms.
7b-2b=5b. 4-2=2.
Your answer is going to be A, 5b+2.
3. 6c+8+3-2d
C and D aren't like terms, so they can't be combined. But, you have whole numbers that can be. 8+3=11.
Your answer will be A, 6c-2d+11.
4. 8e+4-3+9e. You have like terms again.
8e+9e=17e. 4-3=1.
Your answer will be A, 17e+1.
This should get you started and if you have more questions, feel free to ask. I hope this helped. Best of luck!