\[\boxed{\mathbf{14.}}\]
\[\textbf{а)}\ 2 \cdot 6 = 12\]
\[2 \cdot 4 = 8\]
\[3 \cdot 2 = 6\]
\[3 \cdot 3 = 9\]
\[3 \cdot 5 = 15\]
\[4 \cdot 4 = 16\]
\[4 \cdot 3 = 12\]
\[4 \cdot 5 = 20\]
\[\textbf{б)}\ 3 \cdot 2 \cdot 2 = 6 \cdot 2 = 12\]
\[2 \cdot 2 \cdot 5 = 4 \cdot 5 = 20\]
\[2 \cdot 3 \cdot 3 = 6 \cdot 3 = 18\]