title: java script for a drop down selected index change
body: <p>i  2 Dropdown  controls  and  1  text  box
   In drop down1  one  i have the  values like  11.00,11.30,12.00,12.30,13.00, 13.30
   In drop down2  one  i have the  values like  11.30,12.00,12.30,13.00, 13.30, 14.00</p>
  
  <p>once the user  selects the  values  in drop down 1 and  drop down 2  an  event  will  fires in drop  down 2. where  the selected vales from drop down 1 and drop down 2   are  taken. the     dropdown1 value is  subtracted  from  dropdown2 value .<br>
   if condition comes like  11.30 - 11.00= .30   if  .30 is  the  result it  should  be  shown as  .50   as  a result in text box
   if condition comes like  11.00 - 10.30= .70   if  .70 is  the  result it  should  be  shown as  .50   as  a result in text box</p>
  
  <p>this  condition should as    work in  javascript </p>
  
  <p>if any  one  know s  how   to  do  it,  help  me  out
    thank  you </p>