\[\boxed{\mathbf{5}\mathbf{.}}\]
\[1)\ 30,\ 27,\ 24,\ 21,\ 18,\ 15,\ 12,\ 9,\ 6,\ 3.\]
\[2)\ 40,\ 36,\ 32,\ 28,\ 24,\ 20,\ 16,\ 12,\ 8,\ \]
\[4.\]