How to use in a formula a value of a specific record from a separate table

Hello!

I would like to have a table that contains variables.

For example, i'll have a variable there called 'Second_product_discount_var'.
So i can use it in formulas.

For example a formula field like 'total_product_cost' could be calculated like:

If 'used_product_quantity'=2 then
'product_cost'+('product_cost'*'Second_product_discount_var')
else 'product_cost'

But i dont know how to mention that record in the formula if that Variables table is not referenced. And i dont think it has to be referenced.

Thanks a lot!