Equalising numbers

I would like to equalise a set of 3 (or maybe more) numbers.

For example I would like
6,4,2
to become
4,4,4

or

9,0,5
to become
5,4,5

or

0,3,0
to become
1,1,1

If I had 2 numbers the the sum is simple. I'd subtract the lower number from the higher. Then half that number and add it to the lower and subtract from the higher.
8,6 would become 7,7

But how can I equalise 3 or more numbers?

How can I do this?

Thanks!