Subtract one column from constant value

Hi!

So I have a column as Driver Name, Avg Driver Score.

I want to perform (Avg Driver Score) - 4.85 and this value should appear next to all the drivers selected for a particular month.

When I do Measure = [Avg.DriverScore]-4.85, I get a list with all the driver names and not just the drivers selected for that Time frame.

For e.g. 

I want something like this;

But instead I get list of all the drivers that are not a part of the selected time frame like this: