How to change the way JS executes the calculation, if one HTML element is hidden or not being displayed?

I was wondering how do I introduce a secondary formula in my calculation if HTML element is hidden from on click event.

For instance, if I have selected "Two Way Bet" , then r2 variable in Javascript is not used in any of the calculations for the final result.

As far as I have gotten to understand, I need to use If else statement, however I don't even know where to begin here.

r1 = document.getElementById("homeid").value;
r2 = document.getElementById("drawid").value;
r3 = document.getElementById("awayid").value;

  
document.getElementById("1").innerHTML=((1/r1)*100).toFixed(2)+" % to win";
document.getElementById("2").innerHTML=((1/r2)*100).toFixed(2)+" % to win";
document.getElementById("3").innerHTML=((1/r3)*100).toFixed(2)+" % to win";

    r11=(1/r1)*100;
    r22=(1/r2)*100; (This calculates the draw stakes.
    r33=(1/r3)*100;
    
  
s=(200-(r11+r22+r33))/100;
stake = document.getElementById("stake").value;  
s1= (stake*s)*(r11/100); 
document.getElementById("4").innerHTML= s1.toFixed(2)+" $";
  
stake = document.getElementById("stake").value;  
s2= (stake*s)*(r22/100); 
document.getElementById("5").innerHTML= s2.toFixed(2)+" $";  
  
stake = document.getElementById("stake").value;  
s3= (stake*s)*(r33/100); 
document.getElementById("6").innerHTML= s3.toFixed(2)+" $";
 
  
    vuelve1 = (r1*s1)-stake;
    vuelve2 = (r2*s2)-stake;
    vuelve3 = (r3*s3)-stake;  
  document.getElementById("homest").innerHTML= "Home Profit: "+vuelve1.toFixed(2);
  document.getElementById("drawst").innerHTML= "Draw Profit: "+vuelve2.toFixed(2);
  document.getElementById("awayst").innerHTML= "Away Profit: "+vuelve3.toFixed(2);
  
  document.getElementById("return").innerHTML=200-(r11+r22+r33).toFixed(2);