Javascript - Hidden maths answer.

The script below generates random numbers, and calculates the answer.

The next thing is that I want to have the answer HIDDEN and place a text area there. Then you have to input an answer and when the answer is correct, it should make the answer green.

I know it is possible, but I've searched on the internet for it without success, so I'm creating a question instead.

Here's the script:

<div id="breuken"></div>
 
 $(function () {
     var number = document.getElementById("breuken");
     var i = 0;
     for (i = 1; i <= 10; i++) {
         var sRandom = Math.floor(Math.random() * 10);
         var fRandom = Math.floor(sRandom + Math.random() * (10 - sRandom));
         var calc = Math.abs(fRandom - sRandom);
         number.innerHTML += "" + fRandom + " - " + sRandom + " = " + calc + "<br />";
     }
     number.innerHTML;
 });
 

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