Depends on what you enjoy more (which one is less crap then the other) / get better marks in and (if applicable) which of these subjects relates to what you want to study after you finish year 12. I would keep business and drop modern.
Based on the information that you've given us I would say keep both, however, consider
- Teacher quality
- Number of students in previous years getting band 6s, 5s etc in respective subjects
- Your ranking/marks for the respective subjects
- How you are performing in your other subjects (ranks/how well your school performs in the subjects)
I found that the majority of my students who keep six subjects as opposed to dropping to five are more productive with their time since they have less of it. This cuts out procrastination and often results in their extra subject helping them to develop skills that help with their other subjects. Just some food for thought