\[\boxed{\mathbf{1}\mathbf{.111}}\]
\[\textbf{а)}\ 40\ :5 = 8 \cdot 3 = 24\ :6 =\]
\[= 4 + 46 = 50\]
\[\textbf{б)}\ 72\ :8 = 9 + 11 = 20\ :5 =\]
\[= 4 \cdot 9 = 36\]
\[\textbf{в)}\ 28\ :7 = 4 \cdot 8 = 32 + 8 =\]
\[= 40\ :10 = 4\]
\[\textbf{г)}\ 56\ :8 = 7 + 13 = 20\ :4 =\]
\[= 5 \cdot 8 = 40\]