getting a value from a checkbox and adding to a total depending on selection [closed]

I am new to programming... but I've been scrounging the internet for a few hours now trying to see if what I want to do is possible. What I want is to take a value from a checkbox, and depending on the option in the select, have it add a different number to a total.

I think I'll need an if statement for that, but I am not sure how to go about doing it. Does anyone know where I can start?