Answer 1

1. Do you mean insert a new column, append to an existing column (or maybe sum the entire column)?

2. Do you have some code + test data, after your previous question about getting started?
https://www.sololearn.com/Discuss/1137404/?ref=app

That would help a lot. There may be a few ways to approach this, but starter code helps people contribute at the right level for the task, for example: @Tin Le hinted that delimiters aren't always commas, or maybe it's worth leveraging data structures or even an external library. These choices can better fit with your code / not overpower the task if there's a CodePlayground code for answers to use.