Q:

JS addition game: how do I display 4 possible answers, 3 of them are random and 1 is the correct answer ? (Codepen included)

I am building a game out of JS. the rules of the game are simple: you are asked what (num1) + (num2) equals (as you can see in the codepen).
In the game you have 4 possible choices to answer the question.
We're I'm stuck right now is creating those possible options: I would like to display three random numbers that are false and one number that is the correct sum.
my JS:
var num1 = Math.floor((Math.random() * 30) + 10);
var num2 = Math.floor((Math.random() * 30) + 10);
var result = num1 + num2;

document.getElementById('field1').innerHTML = num1;
document.getElementById('field2').innerHTML = num2;

var options = {
    option1: document.getElementById('option1'),
    option2: document.getElementById('option2'),
    option3: document.getElementById('option3'),
    option4: document.getElementById('option4'),
}

Here is my codepen:
https://codepen.io/teenicarus/pen/Oxaaoe
How do i do this?
I appreciate all answers

A:

Here is a solution you can refer. 

document.addEventListener("DOMContentLoaded", function(event) { 
  var num1 = Math.floor((Math.random() * 30) + 10);
    var num2 = Math.floor((Math.random() * 30) + 10);
    var result = num1 + num2;

    document.getElementById('field1').innerHTML = num1;
    document.getElementById('field2').innerHTML = num2;
    var opts = [];
    for(var i=0;i<3;i++){
      opts.push(findRandom(result,opts));
    }  
    opts.push(result);
    opts.sort();  
    for(var i=1;i<5;i++){ 
     document.getElementById('option'+i).innerHTML = opts[i-1];
    }  
});

function findRandom(n,opts){
  var result = 0;
  while(result !=n && result == 0){
    result = Math.floor(Math.random() * (n + 1)); 
    if(opts.indexOf(result) >0){
      result = 0;
    }
  }
  return result;
   
}
.App {
  text-align: center;
}

.App-logo {
  animation: App-logo-spin infinite 20s linear;
  height: 60px;
}

.App-header {
  background-color: #222;
  height: 180px;
  padding: 20px;
  color: white;
}

.App-intro {
  font-size: large;
}

@keyframes App-logo-spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.text-info {
  color: #fff;
  font-weight: bold;
  font-size: 2.1rem;
}

.question {
  font-size: 2rem;
}

.options {
  margin: 5%;
  display: flex;
  margin-right: -12px;
  margin-left: -12px;
  flex-direction: row;
  flex-wrap: wrap;
  align-items: stretch;
  flex: 1 0 auto;
}

.fields {
  display: flex;
  padding: 12px;
  flex-direction: column;
  justify-content: flex-start;
  align-items: stretch;
  flex: 1;
}

.field-block {
  display: flex;
  min-height: 160px;
  padding: 10%;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  /*flex: 1 0 auto;*/
  border-radius: 4px;
  background-color: #f9bad0;
  font-size: 6rem;
  color: #fff;
  cursor: pointer;
}

.quiz {
  color: #ddd;
  margin: 2%;
  background-color: #ec1561;
  padding: 2%;
  width: 90%;
  position: relative;
}

.button {
  display: flex;
  height: 48px;
  padding-right: 16px;
  padding-left: 16px;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  flex: 0 0 auto;
  border-radius: 4px;
  background-color: #2fcaaa;
  box-shadow: 0 1px 3px 0 rgba(0, 0, 0, .05), 0 2px 12px 0 rgba(0, 0, 0, .1);
  transition: box-shadow 200ms ease-out;
  color: #fff;
  font-weight: 500;
  text-align: center;
  cursor: pointer;
}

.quiz .after {
  position: absolute;
  top: 5%;
  left: 5%;
  width: 90%;
  height: 80%;
  /*display: none;*/
  color: #FFF;
  text-align: center;
  align-items: center;
  justify-content: center;
  display: flex;
  opacity: 0.8;
  font-size: 3rem;
}

.correct {
  background-color: green;
}

.wrong {
  background-color: #D91E18;
}

.hide {
  display: none !important;
}
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Adding 2 Numbers | Happy Learning!</title>
    <link rel="stylesheet" href="style.css">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.5.2/animate.min.css">
  </head>
<body>
 
<a href="https://happy-learning.herokuapp.com/ " target="_blank"><img alt="Join Slack" height="40" width="139" src="http://i.imgur.com/0Lne5Vr.png"/></a>
<div>
 <h1>Adding Game</h1>

 <p id="demo">In this lecture, we will cover the game to add 2 numbers.</p>
</div>
<hr>

<div class="quiz">
  <div class="quiz-content">
    <div class="question">
    What is the sum of <span class="text-info" id="field1">5</span> and <span class="text-info" id="field2">5</span>?
    </div>
    <div class="options">
      <div class="fields animated zoomIn">
        <div class="field-block" id="option1">
          10
        </div>
      </div>
      <div class="fields animated zoomIn">
        <div class="field-block" id="option2">
          10
        </div>
      </div>
      <div class="fields animated zoomIn">
        <div class="field-block" id="option3">
          10
        </div>
      </div>
      <div class="fields animated zoomIn">
        <div class="field-block" id="option4">
          10
        </div>
      </div>
    </div>
    <div class="after hide" id="after">

    </div>
    <div class="play-again">
      <a class="button">Play Again</a>
    </div>
  </div>
</div>

<script src='index.js'></script>

</body>
</html>

