it has a sum that is greater than the sum of 6+4 but less than the sum of 8+5

Question

What fact is max thinking of

Answer 1

If the sum is greater than 6+4 it is greater than 10; and if it's less than 8+5 it's less than 13; so the sum must be 11 or 12. A sum implies the addition of two numbers so Max is probably thinking of 7+5 or 6+5. I'd go for 7+5 because 7 is between the 6 of the first sum and 8 of the second.