\[\boxed{\mathbf{1.}}\]
\[\boxed{\mathbf{2.}}\]
\[160\ :40 \cdot 23 = 4 \cdot 23 = 92\ (Ч)\]
\[(815 - 609)\ :2 = 206\ :2 =\]
\[= 103\ (В)\]
\[18 + 728\ :4 = 18 + 182 =\]
\[= 200\ (Ч)\]
\[960\ :8 \cdot 5 = 120 \cdot 5 = 600\ (С)\]
\[725 + 1000\ :8 = 725 + 125 =\]
\[= 850\ (Т)\]
\[(217 + 83)\ :15 = 300\ :15 =\]
\[= 20\ (Ь)\]
\[516\ :3 - 72 = 172 - 72 =\]
\[= 100\ (Н)\]
\[405\ :5\ :9 = 81\ :9 = 9\ (М)\]
\[650 - (423 + 77) = 650 - 500 =\]
\[= 150\ (У)\]
\[147\ :(84\ :12) = 147\ :7 =\]
\[= 21\ (А)\]
\[861\ :7\ :3 = 123\ :3 = 41\ (Е)\]
\[Пословица:\]
\[Ученье - свет,\ а\ \]
\[неученье - тьма.\]