Help to create book selling calculation using firebase

Hello,I'm trying to create a selling book app using automatic calculation,does someone here can help me since i'm still a newbie and try using tinyDB but does not work.perhaps need help with firebase

Here is a fruit selling app that works off TinyDB.

If you want to do calculations on firebase, then you will need to use the server side / back end functions facility and install firebase cli on your computer.

Otherwise, do the calculations on your device, and upload the result to firebase. (or download data from firebase to do the calculations)