What is the explicit formula in algebra 1

It may be written in either subscript notation a n, or in functional notation, f (n). Sequence: {10, 15, 20, 25, 30, 35, ...}. Find an explicit formula. This example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).

The year before the 10s so it was like when caveman were alive