Calculate percentage of same group

[kirawaters]

Hello, I'm trying to figure out how to calculate the percentage of the same group using a measure. If I can't do it in a measure, I at least need to be able to do it in a column on the same table. If my data were split between two tables, I would use PercentageofItem = thistable[sold]/sumx(filter(thattable, thattable[item#]=thistable[item#]. 

Below is an image of what I'm trying to do: my table has products, and the number of those products sold by which salesperson. I need to know for each line what percentage of sales it is for it's type of product. My dataset includes thousands of products and thousands of people, so I don't want to see it the way the summary shows it, just on a line-by-line basis how much of the total of that type of product is this line referring to? I want the solutions in row D that can be found using the excel formula there.

[amitchandak]

@kirawaters , Try a measure like

divide(sum(thistable[sold])/calculate(sum(thistable[sold]) , filter(allselected(thattable), thattable[item#]=max(thistable[item#] ))))

[kirawaters]

That's an interesting solution. The problem is that thattable doesn't exist. Everything is on thistable. Is there a way to do it with all of the relevant data being on a single table?