Hey there @rennielee5 and welcome to the forum!
Shawn is pointing you in the right direction!
Just wanted to also share this post, where I shared a tutorial that may be helpful for you right now. It explains how you can update the variable, and also trigger a query to update your back end. You can easily add another query there to make the other calculations you mentioned.
We're here to help, but as Shawn mentioned, it would be great if you can provide more screenshots, and, in particular with regards to the downstream calculations you're trying to do, maybe sharing a JSON of yorur table's data and what changes you would liek to achive.
Cheers!