Given the arithmetic sequence 8, 5, 2, - find s20

The formula to find any term of an an arithmetic sequence is given by
==(n-1)d,
where we have first term =8, 
and d which is the common difference , and n is the term we need to find (in our case is 20)
the difference d=3, as you see each number is the previous minus 3
for S20=8+(20-1)*(-3)=8+(19)*(-3)=8-57=-49
S20=-49, this the 20th term

64

Step-by-step explanation:

Because it my lucky number