I buy 7 boxes of CDs and 5 boxes of DVDs. Edit the invoice using the spreadsheet by inserting the price of the items and using only the cell reminder to complete the invoice. (ex: ‘= A1 + B2’ which means that the box which will contain this expression will automatically display the sum of box A1 and box A2)
I strongly advise you to open an account on Scratch. The majority of secondary school teachers work with this site, in addition to being fun, it will allow you to explore and create your own program. If you are starting from scratch, and you prefer to learn programming by challenges, games and small exercises, I recommend algoblocs and blocky games.
Example of exercise on this platform:
Example of exercise with correction