What letters will fill the blank?

Z, X, V, T, R, __,__

In the following question, select the missing number from the given series.

1161, 1164, 1168, 1173, 1179, ?

In the following question, select the missing number from the given series.

3, 5, 7, 11, 13, ?

In the following question, select the missing number from the given series.

108, 104, 100, 96, 92, ?

In the following question, select the missing number from the given series.

14, 17, 21, 24, 28, 31, ?

In the following question, select the missing number from the given series.

178, 172, 166, 160, ?, 148

In the following question, select the missing number from the given series.

64, 75, 86, 97, ?, 119

In the following question, select the missing number from the given series.

12, 17, 34, ?, 78, 83, 166

In the following question, select the missing number from the given series.

147, 149, 152, 156, 161, ?