## Intermediate Algebra for College Students (7th Edition)

$-118$
Here, $a_1=15, d=-7$ n-th term an arithmetic sequence can be calculated as: $a_n=a_1+(n-1)d$ Thus, $a_n=15+(n-1)(-7)$ Also, $a_{20}=15+(20-1)(-7)=15+-133=-118$