JSFiddle - React, Tailwind, and code Playground

HTML

<table>
 <tr>
  <td>Option 1</td>
  <td><input type="checkbox" name="option1" value='10000' onclick="myCalc(this)"></td>
  <td>10,000</td>
 </tr>
 <tr>
  <td>Option 2</td>
  <td><input type="checkbox" name="option2" value='5000' onclick="myCalc(this)"></td>
  <td>5,000</td>
 </tr>
</table>

<p>Total = <span id="Total"></span></p>

JavaScript

curVal = 0;
document.getElementById('Total').innerHTML = curVal;
function myCalc(e){
 newVal = parseInt(e.value);

 if (e.checked) {
  curVal = curVal + newVal;     
  document.getElementById('Total').innerHTML = curVal;
 } else {
  curVal = curVal - newVal;  
  document.getElementById('Total').innerHTML = curVal;
 } 
}