Which one will replace the question mark?

In this number-pattern series, each figure links its two upper numbers to the number below it through one fixed arithmetic rule: divide the sum of the two upper numbers by a constant divisor to get the lower number. The rule is confirmed by the two complete figures and then applied to find the missing value in the third.

1. First figure: 15 and 12 are the upper numbers, and 3 is the lower number. (15 + 12) ÷ 9 = 27 ÷ 9 = 3, which matches.

2. Second figure: 44 and 28 are the upper numbers, and 8 is the lower number. (44 + 28) ÷ 9 = 72 ÷ 9 = 8, which matches and confirms the divisor is 9 in both cases.

3. Third figure: apply the same rule — divide the sum of 64 and 53 by 9 — to find the missing lower number: (64 + 53) ÷ 9 = 117 ÷ 9 = 13.

Cross-check by reversing the operation: multiplying each lower number by 9 must return the sum of its upper pair — 3 × 9 = 27 = 15 + 12, and 8 × 9 = 72 = 44 + 28 — and indeed 13 × 9 = 117 = 64 + 53, confirming the missing number is 13.