The given formula that models the number of songs in Martin's iTunes collection is:
![N(m)=200+15m](https://img.qammunity.org/2023/formulas/mathematics/college/p7f4sce0ebqxescnqajkus50u157foy1cr.png)
Where m is the number of months.
We can interpret the terms in this formula as: 200 is the current number of songs in Martin's collection, and 15 is the number of new songs Martin adds every month.
We can prove this by replacing m=1, so:
![\begin{gathered} N(1)=200+15*1 \\ N(1)=200+15 \\ N(1)=215 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/bgzaekk0g6k2kng4xmjksigwyl7pkbv1qx.png)
So, in the first month, Martin will have 215 songs, for a total of 15 new songs.
The answer is: Every month, Martin adds 15 new songs.