### Home > CCAA8 > Chapter cca10 > Lesson cca10.2.3 > Problem10-56

10-56.

How many terms are in the arithmetic sequence shown below? Homework Help ✎

$15,\ 7,\ −1,\ −9,...,\ −225$

Write an equation for the arithmetic sequence using $a_n−m\left(n-1\right)+a_1$

Let $a$ sub $n=−225$ and solve for $n$.