Plot difference between two rows based on slicer selection

Hello!

I am working to plot the difference between 2 rows based on user selection.

Users would select language 1 and language 2, and the chart needs to display the difference between the selected values.

Here's sample data,

Language | Points

Python | 10

RUST | 12

Java | 8

R | 6

e.g. Python - R should output "4"
       R - Python should output "-4"
       Python - RUST "-2" etc

Appreciate your inputs!