How can I define these two variables?

Question

I always use a lot of functions and confuse myself, and I know you can't use a variable you defined in one function in another function, but I think I need a more experienced programmer to tell me how I can define firstNumber and secondNumber in operator without throwing anything else off balance. Thanks in advance
https://code.sololearn.com/WS5nmS4omS32/?ref=app

Answer 1

This is your correct code. Try it.☺😋
https://code.sololearn.com/W94yU75P94oT/?ref=app

Answer 2

I don't think your code sent properly Vitality Angelov

Answer 3

Var x=your number here