The Meaning of 2 Numbers - challenge

What is the arithmetic mean of 2 numbers, say a and b? If I asked you to write down the algebraic expression, you would probably write x=(a+b)/2, where x is the arithmetic mean.

So, the arithmetic mean of 7 and 9 is 16/2 or 8.

Try this rubric:

1. Find the absolute difference between the 2 numbers
2. Add half that difference to the smaller of the numbers
3. The result is the arithmetic mean.

Example, 7 and 9:

1. 7-9=-2; abs(-2)=2
2. 2/2 = 1; 7+1 = 8.
3. Mean of 7 and 9 is 8.