61 57 50 61 43 36 61

• A. 22 15
• B. 31 61
• C. 29 22
• D. 27 20
• E. 29 61

Answer: (C)

This is an alternating repetition series, in which a random number, 61, is interpolated as every third number into an otherwise simple subtraction series. Starting with the second number, 57, each number (except 61) is 7 less than the previous number.