SAS Equivalent of Macro variable in Python

[AI_ML_Neophyte]

I am writing code to simulate different scenarios. However, it gets cumbersome to type in the values for different scenarios. I was hoping I could use something similar to a SAS Macro variable so that I can change the values at the top and the bottom would invoke (via the macro variable) the changes

I've tried various options but no luck

/* Defining the Macro Variable */
%LET a = 10;
%LET b = 5;

/* Invoking it */
x = &a + &b
The answer is 15

thanks

PC