Write a Formula for the General Term (The Nth Term)of $r a _ { n }$

Multiple Choice

Write a formula for the general term (the nth term) of the arithmetic sequence. Then use the formula for $r a _ { n }$ to find $a _ { 20 }$ , the 20th term of the sequence.
- $30,25,20,15 , \ldots$

A) $a _ { n } = 35 - 5 n ; a _ { 20 } = - 65$
B) $a _ { n } = 30 - 5 n ; a _ { 20 } = - 70$
C) $a _ { n } = 5 n - 35 ; a _ { 20 } = 65$
D) $a _ { n } = 5 n - 30 ; a _ { 20 } = 70$