Question 8
Find the missing number.
**Editorial input format:** Use the editorial rules described in the solution: outside-number sum for a, main-diagonal symmetry for b, and equal row differences for c. Enter the three answers in a–c order, separated by commas.
**Editorial input note:** Use no spaces before or after commas.
**Editorial input format:** Use the editorial rules described in the solution: outside-number sum for a, main-diagonal symmetry for b, and equal row differences for c. Enter the three answers in a–c order, separated by commas.
**Editorial input note:** Use no spaces before or after commas.