§ Задание 28
\[\boxed{\mathbf{28.}}\]
\[19,\ 20;\]
\[29,\ 30;\]
\[39,\ 40;\]
\[49,\ 50;\]
\[59,\ 60;\]
\[69,\ 70;\]
\[79,\ 80;\]
\[89,\ 90;\]
\[9,\ 10;\]
\[99,\ 100.\]
\[\boxed{\mathbf{28.}}\]
\[19,\ 20;\]
\[29,\ 30;\]
\[39,\ 40;\]
\[49,\ 50;\]
\[59,\ 60;\]
\[69,\ 70;\]
\[79,\ 80;\]
\[89,\ 90;\]
\[9,\ 10;\]
\[99,\ 100.\]