How to store values in buttons selected and add them up at the end in Kotlin

Question

I followed this tutorial on making a quiz app since it seems to have a lot of the functions I want, but I want to modify, but I'm unsure how. Can someone assist? https://www.youtube.com/watch?v=b21fiIyOW4A I will attach an image showing what I'm trying to accomplish. So screen 1 will ask for the persons name or email. The next screen will ask for how many photos they will want edited,, next screen will ask for turn around time on editing etc... Each of these will affect the cost of their photography package they want. How can I store values for each button selected.

Because right now it is a quiz app. So it says incorrect or correct for each selection. I want that eliminated and just stored and tallied at the end screen showing how much a photography package would cost them for example. The last screen will display the total. Example Photoshop