As per the details in the question the series is in the form of
First term + Second term = Third term
⇒ 7 + 9 = 16;
Second term + Third term = Fourth term
⇒ 9 + 16 = 25;
Similarly , we can find all others terms also.
Third term + Fourth term = Fifth term
⇒ 16 + 25 = 41;
Fourth term + Fifth term = Sixth term
⇒ 25 + 41 = ?
∴ ? = 66
Fifth term + Sixth term = Seventh term
⇒ 41 + 66 = 107
Sixth term + Seventh term = Eighth term
⇒ 66 + 107 = 173
Hence , Sixth term = 66
