How to script an if/then statement with a check box and calculated form?

Any help would be much appreciated! (It's time-sensitive, as well, so the quicker the better.) I'm using Livecycle Designer 8.0.

I'm looking to script an if/then statement and apply it the the check box next to "New member". Here's what I want it to do:

- If a user checks "New member" check box, then a calculated number appears in the "New member's dues" numeric field.

- Additionally, the "New member's dues" numeric field should be calculated as a sum of "Annual dues (total)" multiplied by 0.50.)

- Moreover, is there a way to take this a step further and make the "New member's dues" numeric field AND the two check boxes ($198 minimum, $5,150 maximum) hidden unless the "New member" check box is checked?

I'm pretty familiar with the if/then javascripts, but for some reason I just can't figure this one out.

Thank you, in advance, if you can help!