How can I make more arrays in my math quiz?

I want to make a math quiz. I have 3 questions and 3 arrays. I want to make more questions and arrays in loops.
Here is working fiddle:
https://jsfiddle.net/ysbxcqu8/

Here is my code with missing eval():

function getResults() {

  const questionsCount = document.getElementsByClassName("questions").length;
  var amountCorrect = 0;
  let signArr = [];
  var x = new Array(3);
  for(var i = 0; i < questionsCount; i++) {
    var radiosName = document.getElementsByName('answer' + (i + 1));
    x[i] = [];
    x[i].push( document.getElementsByClassName("first")[i].innerText );
    x[i].push( document.getElementsByClassName("second")[i].innerText );
    x[i].push( document.getElementsByClassName("resultSpan")[i].innerText );
    
    for (var j = 0; j < radiosName.length; j++) {
      if( i == 0 )
        signArr.push(document.getElementsByClassName("sign")[j].nextSibling.innerText);
      var radiosValue = radiosName[j];
      
      if (radiosValue.checked) {
        if ( eval( ) ==  ) 
        {    
          radiosValue.value = "correct";
          amountCorrect++;
          console.log("ok");
        }else{
          console.log("wrong")
        }
      }  
    }
  }
  document.getElementById('results').innerHTML = "Correct answers: " + amountCorrect;
}

I don’t know how to write an if instruction with eval function. Could you help me, please?