For this case we have the following arithmetic sequence:
[tex]a_ {n} = 15 + 5 (n-1)[/tex]
To write in function form, we apply distributive property to the terms within parentheses:
[tex]f (n) = 15 + 5n-5[/tex]
Different signs are subtracted and the major sign is placed.
We simplify:
[tex]f (n) = 5n + 10[/tex]
Answer:
[tex]f (n) = 5n + 10[/tex]
Option C