7 4 5 9 20 52.5 3 (a) (b) (c) (d) (e) Which of the following numbers will come in place of (c)?

As per the details in the question the series is in the form of
First series :-
First term = 7
Second term = First term × 0.5 + 0.5
⇒ Second term = 7 × 0.5 + 0.5 = 4
Third term = Second term × 1 + 1
⇒ Third term = 4 × 1 + 1 = 5
similarly , we can find the all others terms .
Second series :-
First term = 3
Second term = First term × 0.5 + 0.5
⇒ Second term = 3 × 0.5 + 0.5 = 2
Third term = Second term × 1 + 1
⇒ Third term = 2 × 1 + 1 = 3
Fourth term = Third term × 1.5 + 1.5
⇒ Fourth term = 3 × 1.5 + 1.5 = 6
Hence , the place value of ( c ) is 6 .