No, you dont use a different base CPI for the two calculations. There is only one question. Is the base CPI 100 or 130. If its 100, then the answer is A, if its 130 then the answer is C.
Anyway, I'm confident that I got at least 17/20, not sure about 12, 19, 20 though.
I Put 12.C
19.A
20.D