Comments by Anvitha Rao (Top 1 by date)

got the solution:
<script type="text/javascript">
function AppendValues(form) {
var txtunits = form.txtunits.value;
var txtdevicecost = form.txtdevicecost.value;
var txtinstallation = form.txtinstallation.value;
if (txtunits != '' && txtdevicecost != '' && txtinstallation != '') {
var result = (txtunits * txtdevicecost);
form.txtpaymentamount.value = parseInt(result) + parseInt(txtinstallation);
}
}
</script>