What does 20% off the regular price mean

Areal estate agent earns $32,000 a year plus $1,000 for each apartment he sells. write an equation that shows the relationship between the number of apartments abe sells,n, and the total amount he earns in a year,e. what is the total amount abe would earn from selling 10 apartments in one year

What is the binomial expansion of (2x-3)^5

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie