Sum value from several queries to new one value cell

Hi folks,
I’m using prometheus with Grafana, and I have one table with three queries where is same values for all queries hostname.

I need average of that values by hosts.
Can I create new one column where I can sum all value and devide with 3 by hostname ?

You can see here on image, left is hostname, on the right side was value for three queries. I need new one column with sum (A+B+C) / 3

Thank you in advanced.