Answer:
-1,7,15,23,31,39
Explanation:
39-31=8
So keep adding 8 to the first number, in your case it is -1 so -1+8= 7. Then add 8 to the 7 to get 15, after that add 8 to the 15 to get 23. To make sure that your answer is right add 8 to 23, which will give you 31.