Really Stuck with Some Calculations

A am new to the DAX Languge and Power BI in gerneral mostly messing around with the power m Query/data shaping side, but I suspect the reason it fails is that the related goes from one to many then many to one. So the way I see it if you go from the one employee and his target amount to the next table using the employee number you now have several employee id's possibly related to the currency you want to convert. I think this is where the related function gets confused. Isn't there a way to use the currency code in the sales bonus table to directly compute the exchange rates? In power M I would create a fucntion that simply uses the currency codes in each row in the sales table to select the row in the fx rates table.  I would be suprised if there is not an analog in DAX.   I hope you figure it out.