Answer:
an=4n+4
Explanation:
well it goes up by 4 every month so thats 4n, since 8, 12, 16.
but since we need to know the explicit formula we need to find the term before 8. So Its adding every month so the month preious to a1 is gonna be 4. Since 8 - 4 is 4.
an = 4n + 4