Well, I saw my teacher solving the test herself, and then grading papers off of her paper that she solved. My teacher made the answer key for the tests.
It goes by 8!
If u see, 4 + 8= 12 +(another) 8 = 20! It skips 8 every time!
If u were to continue it, 20 + 8 = 28 and so on!
The difference is the sum of the number totalled.
Hope this helps!
its not 100 points it 8 but i will still help you
the answer is 7.2 i believe