(hello, I just answered your previous question--some stuff will sound similar because we are applying the same concept :) )
We know that the nth term of the sequence is 18 - 8n
the "nth" term of a sequence means that you can plug in the term place to get the term value (ex. if the nth term is n + 2, we can plug any term in {let's say, the eighth term, 8 + 2 = 10 ; to get our term's value} )