Question

Why can't you compare 5 minutes in 240 seconds without making some kind of change

Answer 1

You have to have the same unit of measure. Here your units are "minutes" and "seconds". In order to compare the two, you must change to 240 seconds into minutes (dividing by 60 = 4 mins) OR change the 5 minutes into seconds (multiply by 60 to give you 300 seconds)