Set up the following system: microsoft office has a $20 purchase fee and costs $10 per month. it’s competitor chaffey office has a 10$ purchase fee and costs 12$ per month. let microsoft office be c(m). use m to represent the number of months.

Well, let's say you want to see how much it would cost to have Microsoft vs. Chaffey for a year. The equation for Microsoft would be: 
20 + 10m 
Chaffey would be: 
10 + 12m 
You would put 12 into m (12 months in a year) for both equations and find that it would be more expensive to have Chaffey for a year.