I'm stuck with a simple expression creation problem. I'd like to express odds by removing values from $100$ and arriving at a number. Every variable I use has value, that can either be $+10$ or $-10$, for instance. How do I factor this into an expression? If I do it like this:
$$R = 100 - (x_1 + x_2 + x_3)$$
I'll run into an issue if one of my variables $x_i$ is $+10$; it's supposed to add 10 instead of removing it (+ and - would give -), thus impacting my results. I assume this is something rather simple but my math knowledge is very insufficient.
Thanks in advance.