What will come in place of the question marks (?) to complete the given series logically using only addition and subtraction operations? 23, 30, 27, 34, 31, ?, ?

What should come in place of '?' in the given number series? 120, 136, 104, 152, 88, ?

Find the missing number in the following sequence: 36, 31, 29, 24, 22, 17, 15, ______

Which number in the following series is wrong? 37, 44, 55, 79, 107