Question

a(n)=−6+3(n−1)


find the 16th term in the sequence

Answer 1

You already have a direct expression for the terms in the sequence: a(n) is exactly the n-th term.

So, if you want the 16th term, you just need to plug n=16:

$a(16)=-6+3(16-1)=-6+3(15)=-6+45=39$