Let a be the first term and d be the common difference of an A.P. A7=−15 and A12=5 (Given) Then, −15=a+(7−1)d[∵A=a+(n−1)d]−15=a+6d ...(i)−5=a+(12−1)d⇒ 5=a+11d ...(ii)Subtracting Eq. (ii) from Eq. (i), ⇒ 20=5d∴ d=520=4Putting d = 4 in Eq. (i),−15=a+6d⇒ −15=a+6×4⇒ −15=a+24⇒ a=−24−15=−39∴ A16=a+(16−1)d⇒ A16=−39+15×4⇒ A16=−39+60∴ A16=21