title: Add values from two textboxes and display the sum in third textbox 3 but value of 1st aor 2nd textbox show in third textbox
body: <p><a href="http://i.stack.imgur.com/n3PvK.jpg" rel="nofollow">enter image description here</a></p>
  
  <p>Add values from two textboxes and display the sum in third textbox 3 but value of 1st aor 2nd textbox show in third textbox</p>