A School Library Opened in 1980

Short Answer

A school library opened in 1980. In January of 2000, they had 16,000 books. One year later, they had 16,840 books. Assuming they acquire the same number of books at the start of each month, give a linear formula for the number of books, N, in the library as a function of the number of years, t, the library has been open.