Difference between lines in Graph

hello,

I have a graph in power bi for values for 10 business measures for 2 accounts.  The graph has 2 slicers, one for the business measures and one for the 2 accounts to choose from.  My two accounts are in a seperate table than my values table and are linked through a relationship. I need to subtract the difference between the 2 accounts to create a 3rd account for each business measure. For example, if my business measure is "Expenses", I need to find the difference between "Expenses Total Acct" and "Expenses Seperate Acct" to greate a 'Expenses General Acct" line. Any ideas for how I would code this to create a new measure/column that references both tables?