Chapter 5 - Linear Functions - Get Ready! - Page 291: 13

$t_{n} = 16 - 3n$

So the formula for finding a term in a sequence is $a + (n-1)d$ where $a$ is the first term, $n$ is the term number, and $d$ is the common difference. The sequence starts with the number $13$, and the common difference is $-3$. So let's plug the numbers into the formula. $t_{n} = 13 - 3(n−1)$ $t_{n} = 13 - 3n + 3$ $t_n = 16 - 3n$