I'm making a sevice request page for a project in my high school web design class, and I was wondering if there would be a way for me to make the form work in such a way that, after the viewer selects all the different settings and features they want, sums associated with these features could be added up to make a total at the bottom. I asked my teacher, but he doesn't know, and couldn't find an aswer on Google

Is this possible with html and css, or would I have to do something fancier?
I'm not sure what information you may need about my page and the like, so if there is something that you need, just let me know in a reply and I'll put it up.
Thanks in advance.