The sum of opposite pairs in each circle follows a sequence. Circle 1: 8+3=11, 6+5=11. Circle 2: 9+3=12, 7+5=12. Circle 3: 9+4=13, 7+6=13. So, the numbers in the last circle must sum to 13. 8+5=13, so the missing number is 5. Wait, the provided hint is different. Following the hint: Opposite pairs in circle 1 total 11. Circle 2 total 12. Circle 3 total 13. So, 6+?=13 -> ?=7. 8+?=13 -> ?=5. Another pattern is: 1st circle, outer: 6,8,5,3. 2nd circle: 7,9,3,5. The outer numbers increase by 1,1,-2,2. This is inconsistent. Following the provided hint for a different puzzle: The opposite pairs in the first circle total 11, in the second 12, and in the third 13. So 8+?=13 gives 5, and 7+?=13 gives 6. So the answer is 5 and 6. This doesn't match the options. The source PDF answer is 10 & 6.