Find the 29th term of the following sequence.

27, 24, 21, 18, . . .

The common difference in this arithmetic sequence is $24 - 27 = -3$. Thus, the $n$th term is given by $a_n = 27 + (-3)(n-1) = 30-3n$, from which $a_{29} = 30 - 3(29) = \boxed{-57}$.