Check Box Changes Totals
===

I need some help with some code. 

I have a form that has three different plans to choose from. Then on the second page you can check a box to add a spouse and the totals need to change. I don't know how to code this. 

**Page One**

This page shows three plan options for a customer to choose from. 

Plan One (Standard) is $99 Setup Fee & $99 a month.

Plan Two (Premium) is $149 & $120

Plan Three (Platinum) is $399 & 185

**Page Two**

This is the form for the end-user to fill out their info. The have an option
to add their spouse with a 35% discount off the monthly.

When they [b]check[/b] the add spouse checkbox I need the totals to change.

**Couples Totals**

If Plan One (Standard) then $198 Setup Fee & $163.35 a month.

If Plan Two (Premium) then $298 Setup Fee & $198 a month.

If Plan Three (Platinum) then $798 Setup Fee & $305.25 a month.

Any idea how to complete this?


    <div class="ccms_form_element cfdiv_checkbox" id="addspouse_container_div"><input type="hidden" name="spouse" value="" alt="ghost">
    <input value="Yes" id="addspouse" title="" type="checkbox" name="spouse" class="label_right">
    <label for="addspouse" class="full_label">Yes! I want to sign up my spouse and take advantage of the 35% discount. (Couples discount applies to spouse's monthly fee only.)</label><div class="clear"></div><div id="error-message-spouse"></div></div>
    
    <div id="math" style="padding-bottom:4px;">
    <p id="sign-up-date-first" style="display: block; "><b>Sign Up Date</b> (Today): <span id="sign-up-date-today" style="border: 0px; background-color: rgb(255, 255, 255); "><?php
    echo date("F dS, Y");
    ?> </span></p>
    
    <p id="signup-fee-result"><b>Review/Setup Fee</b>: <span id="signup-fee-price" style="margin-left: 4px;">$49.00 </span> will be charged: <span class="next-month" id="sign-up-date-six-days"><?php
    $monthlydate = mktime(0,0,0,date("m"),date("d")+6,date("Y"));
    echo date("F dS, Y", $monthlydate);
    ?></span>
    </p>
    
     <p id="signup-price-result"><b>Initial Monthly Fee</b>: <span id="signup-monthly-price">$49.00 </span> will be charged: <span class="next-month" id="sign-up-date-next-month"><?php
    $monthlydate = mktime(0,0,0,date("m"),date("d")+30,date("Y"));
    echo date("F dS, Y", $monthlydate);
    ?></span></p>
    </div>