How to create global variable in Ember Controller

I have my applicationController where I have the following

@action getTable(){
//code to get info when button is pressed
}

@action getRequest(){
    //logic
    let my-expression = aria + bob;
}

I want to capture the my-expression variable so that I can use it in another action decorated function. How can I do that in the most simplest way, in the same controller?