if x bigger than y then return x smaller than y javascript

I'am trying to make a simple calculation generator in prompt window. But it should not generate a negative number as answer, such as: x-y=-answer

My code so far: CodepenLink How it should look like

function myFunction() {
  var randomNumber = Math.floor(Math.random() * 10);
  var nxtRandomNumber = Math.floor(Math.random() * 10);
  var question = prompt("What is:"+ randomNumber+ " minus " + nxtRandomNumber);
  if(nxtRandomNumber > randomNumber){
    return ;
  }
  
  var result = Number(randomNumber) - Number(nxtRandomNumber);
 
    document.getElementById("demo").innerHTML = "Number:" + answer + " was right!";
 
}

<p>Push the button to start </p>

<button onclick="myFunction()">Calculate!</button>

<p id="demo"></p>