[Plugin: Contact Form 7] Extra functionality with dropdown menu (displays text)

Hi,

I have a few requirements that I can’t work out how to do.

First of all, I would like when the user clicks the checkbox, text will appear in a different section.

For e.g. The check box says “click to attend” then further down Total Due $0.00 will change to $90.00 because the check box is clicked. Then if the box is unchecked, the amount goes to $0.00.

The other thing I want to do involves the drop down menu. When no option is selected, no text appears below the drop down menu. But if an option is selected, different text will appear below depending on the option.

Are these possible with this plugin? Any help would be so great because I have no idea how to do this!

https://www.ads-software.com/extend/plugins/contact-form-7/