The Downtown Business Association (DBA) in a certain city plans to increase its membership by a
total of n businesses per year. There were
b businesses in the DBA at the beginning of this
year. Which function best models the total number
of businesses, y, the DBA plans to have as members
x years from now?

y=b+n(x-1)

Explanation:

The initial number of businesses at the beginning of first year was b after every year the number of businesses increases by n but not the first year so the total no of businesses in x years (y) will be the first year b is added to the product of number of businesses added (n) and (x-1) years.