title: How to add values of 2 textboxes and check whether its equal to the third?
body: <p>I have a form where I've multiple <code>textboxes</code> and a <code>dropdown</code> menu with it.</p>
  
  <p>I want to calculate and check whether the sum of these <code>textboxes</code> is equal to third with each textbox has a <code>dropdown</code> menu along with it and the values of that dropdown menu are +1 or -1. For example, I have controls as following:</p>
  
  <pre><code> txt1 with ddl1; txt2 with ddl2; txt3 with ddl3; txt4 with ddl4;
  </code></pre>
  
  <p>I want to check whether:</p>
  
  <pre><code> txt1 * ddl1 = ((txt2 * ddl2) + (txt3 * ddl3) + (txt4 * ddl4))
  </code></pre>
  
  <p>Also, I am using a custom validator and want to check this condition in it. </p>