Subtract two numbers of which one is the result of a sum

Hi everyone,

is it possible to subtract two numbers of which one is the result of a sum? All without using third-party fields where to calculate the sum of the two numbers.

Below is the example:

  • "x-y" where "y" is equal to "a+b" --> so x-(a+b)

a+b could be a result of a rollup sum

Thank you!