Answer: 3
Explanation: Mean is the same thing as average. Well, to find average, we add the two numbers, and then divide them by the number of numbers.
23 + - 17 ← (- and + is the same thing as -)
23 - 17
23 - 17 = 6
Now, we just need to divide that by 2:
6 ÷ 2 = 3
