This is Inline Math using \( ... \) ( x + y = z \in \left{ -1, 1 \right} ) and now using $ ... $ $ x + y = z \in \left{ -1, 1 \right} $ and it should handle the case of giving my friend 2$.
We can also do the same without gaps.
This is Inline Math using \(...\) (x + y = z \in \left{ -1, 1 \right}) and now using $...$