Help me please thanks

What is the common difference in the following arithmetic sequence? 7,3,-1,-5

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

Could someone with number 1 and 2