\[\boxed{\mathbf{Стр.\ 27.\ }еуроки - ответы\ на\ пятёрку}\]
\[\boxed{\mathbf{79.}}\]
\[1)\]
\[2)\]
\[3)\]
\[4)\ \]
\[\boxed{\mathbf{80.}}\]
\[a = 96;\ \ b = 4:\]
\[a\ :b = 96\ :4 = (80 + 16)\ :4 =\]
\[= 20 + 4 = 24.\]
\[\boxed{\mathbf{81.}}\]
\[1)\ x \cdot 16 = 64\]
\[x = 64\ :16\]
\[x = 4.\]
\[Проверка:\]
\[4 \cdot 16 = 64\]
\[64 = 64.\]
\[2)\ x\ :19 = 6\]
\[x = 6 \cdot 19\]
\[x = 114.\]
\[Проверка:\]
\[114\ :19 = 6\]
\[6 = 6.\]
\[3)\ 96\ :x = 8\]
\[x = 96\ :8\]
\[x = 12.\]
\[Проверка:\]
\[96\ :12 = 8\]
\[8 = 8.\]