This question makes no sense, If you mean we are trying to find Rugby, then yes I get that but, Football was only mention once, and once only. I think it's possibly 72 students chose Rugby. The First equation is basically useless unless you are given an Idea of the fact that we need to use the first equation. If that is the case then 12 people chose football. If I didn't help I apologize for that but I was given a question I couldn't make sense of.
