Help! javascript in form

[serenaloce146]

I'm using a form with javascript to calculate some fields together. So far I have this:

<script type="text/javascript">
function calculate(){
var F1num = Number(document.forms[0].F1.value);
var F2num = Number(document.forms[0].F2.value);
document.forms[0].F3.value += (F1num * F2num) / 10;
return false;
}
</script>

<form action="#" method="POST" onsubmit="return calculate()">
<select name="F1">
<option value="0">Width</option>
<option value="20">20</option>
<option value="40">40</option>
<option value="60">60</option>

</select>&nbsp;&nbsp; x&nbsp;&nbsp;
<select name="F2">
<option value="0">Height</option>
<option value="20">20</option>
<option value="40">40</option>
<option value="60">60</option>
</select></p>
<p>

<input type="submit" value="Calculate" >&nbsp;&nbsp;
<input type="text" name="F3" value="$" size="9" >
</form>



I need more though and I'm not sure how to do it. I need two checkboxes added to the form, each equals $50 if clicked. If the viewer clicks a checkbox (or both) I need $50 for each check box clicked added to the total value of F3. Is this possible?

Thanks,
Jess

[serenaloce146]

NEVERMIND!!! I figured it out ^_^