Dividing and applying the value to another

[Naverie]

I'm new to Power BI and haven't had any training so apolygises if the answer is obvious.

I have a set of data

Site	Total Miles
Site1	1000
Site2	2000
Site3	3000
Site4	5000

The total for Site4 needs to be split between the other 3 sites. The data is being pulled from a SharePoint list so needs to be dynamic as it will constantly be updating as well as being able to be shown on different visulations by site and also by user.

I know how I'd do it in SQL but no idea what DAX syntax I need to use. 

Thanks in advance

[amitchandak]

@Naverie ,Can you share sample output in table format?

[Naverie]

So the Central total needs to be divided by 3 and then added to each other the other sites.