An A.P. consists of \(48\) terms in which the \({6}^{\text{th}}\) term is \({18}\) and the last term is \({102}\). Calculate the \({20}^{\text{th}}\) term.
(Hint: If \(a\) is the first term and \(d\) the common difference, then form two linear equations using the given terms and solve for \(a\) and \(d\).)
\( a = \)
\( d = \)
\(a_{20}\) =