Measure to exclude certain rows

Hello!

I have an direct query file I'm working with which is very security restricted (eg. I cannot create new tables/columns etc). 

I've created a matrix that pulls through a grand total of all accounts by financial year and have then used the filters pane to exclude a few accounts. I want to turn this into a measure so I can use it in a line graph to compare against the grand total. I thought this would be simple, however I am stumped. 

The tables used in the matrix are:

Columns: Financial Year (belongs to 'Date - Report' table)

Values: Actual Amount (belongs to 'Transaction Measures' table)

Filter: Code (belongs to 'Account' table) is not 84900, 84901, 84905

I'd be so grateful if someone could suggest a measure that would retrieve the same outcome!