As per the details in the question the series is in the form of
First series :-
First term = 9
Second term = First term × 2 + 1.5 = 19.5
Third term = Second term × 2 + 2 = 41
similarly , we can calculate the all next terms .
Second series :-
First term = 12
Second term = First term × 2 + 1.5 = 25.5
Third term = Second term × 2 + 2 = 53
Fourth term = Third term × 2 + 2.5
⇒ Fourth term = 53 × 2 + 2.5 = 108.5
So, 108.5 should come in place of (c).
