I am having a hard time building the chain onto the premises. How do we know how to chain/connect the statements?

Question, are we doing contrapositives here for fun/learning purposes? When are we expected to do contrapositives or how do we know when ?

Can someone explain to me again the why Kumar was not late? I am not truly understanding the difference between "only if" and "if"

Not sure if this will help anyone out. But before looking at the answers I ask myself, What is it that I need to explain or resolve. I write what I think it is out and then look at the answers.

For example: If unchanged why 3x reported?