Command Help

Basically I want a command that can calculate stuff All I need it to do is a custom command as a calculator. Basically the command itself is the calculator which you can use to calculate stuff for example "/cal 18 + 12, then it'd return 30. Also needs to work with (Multiplying (*) Dividing (/) and subtracting (-) So example /cal 18 + 12 (adding) /cal 18 - 12 (subtracting) /cal 18 * 12 (multiplying) /cal 18 / 12 (division) https://i.imgur.com/qcjr7WG.png (this is what I have so far, I'm really new to MCcreator, so any help is very appericated <3