All I can say is that you have over 75% of your answers is incorrect. The questions incorrect are numbers: 5, 7, 9, 10, 11, 12, 14, 15, 16, 17, and 20. What probably mess you up is probably the negative sign. When you see a negative sign, assume it is a subtraction sign. For example: -2+1 is the same as 1-2 which gets you -1. Same thing for (-3)+5 which is basically 5-3=2. Negative signs add a negative sign, -8+(-8) which is equivalent to -8-8 gets you -16. Negative signs while adding do not ever become a positive number unless it is a negative number subtract a negative number such as -8-(-8) which is the same as -8+8 = 0. If you cannot solve the problem, try to rearrange them due to associative property. It should get you the same answer. I hope this helps. The answers is right below here if you need to check afterwards.
Answers:
5) 4
7) -10
9) -13
10) -1
11) -1
12) -3
14) 4
15) 8
16) -16
17) -5
20) 4
