Answer
General equation is: $a_n=6+(-5)(n-1)$; $-89$
Work Step by Step
Formula to calculate the nth term of an arithmetic sequence is: $a_n=a_1+d(n-1)$
Here, $a_1: $ First term and $d=$ common difference
Since, we have $a_1=6$
Then, our General equation is: $a_n=6+(-5)(n-1)$
$a_{20}=6+(-5)(20-1)=6-95=-89$
