§ Задание 28
\[\boxed{\mathbf{28.}}\]
\[4 \cdot 6 = 24 < 30\]
\[5 \cdot 6 = 30\]
\[5 \cdot 7 = 35 < 40\]
\[6 \cdot 7 = 42 > 40\]
\[3 \cdot 9 = 27 < 50\]
\[6 \cdot 9 = 54 > 50\]
\[\boxed{\mathbf{28.}}\]
\[4 \cdot 6 = 24 < 30\]
\[5 \cdot 6 = 30\]
\[5 \cdot 7 = 35 < 40\]
\[6 \cdot 7 = 42 > 40\]
\[3 \cdot 9 = 27 < 50\]
\[6 \cdot 9 = 54 > 50\]