How to substract with if statement

How can I apply the if statement and calculate a set of radio buttons using JavaScript?

Ok what i would like to do is when the click on yes it will subtract $150 off the total.

<p>Baby Plan<br />
    [radio BPSUBPT id:BPSUBPT class:radio-vertical "Baby Plan $500.00 3 Sessions" "Baby Plan $700.00 4 Sessions"] </p>

<p>Did you have a Newborn session With ADP? <br />
[radio BPSUPQ id:BPSUPQ class:radio-vertical "Yes" "No"]</p>

<p>Baby Plan Totals: <br />
Baby Plan Price: [text BPSUBPP 28/28 id:BPSUBPP]
Discount Amount: [text BPSUDA 10/10 id:BPSUDA]
Balance Amount: [text BPSUBA 8/8 id:BPSUBA]



Total Price: <span id="total"></span>

My java script

<script>
$(document).ready(function() {
    var inputs = $('input[name="BPSUBPT"], input[name="BPSUPQ"]');
    $(inputs).click(function() {
        var total = 0;
        $(inputs).filter(':checked').each(function() {
            // Now including the - sign
            var value = ($(this).val()).match(/$(-?[0-9]*)/)[1];
            if (value) {
                // I'm now ADDing the total
                // total = total + parseInt(value);
                total += parseInt(value);
            }
        });
        $('#total').html('$' + total);
          $('#BPSUBA').val('$' + total);
});
    $('input[name="BPSUBPT"]').click(function() {
        $(this).blur();
        $('#BPSUBPP').val($(this).val());
    })
    $('input[name="BPSUPQ"]').click(function() {
        $(this).blur();
        $('#BPSUDA').val($(this).val());
   });
}); </script>