The first answer is 80, and the second answer is still 65.5. Hope this helps!
she is incorrect the numbers listed above is neither arithmetic or geometric its quadratic sequence . its addition being shown
2+1=3
3+2=5
5+3=8
8+4=12
hope i broke it down enough for you're understanding
I believe the answer for 17 is C. 18 I am not sure how to do. For 19, however, the answer is B. Hope I help, and sorry I can't answer 18.
