\[\boxed{\mathbf{Вариант\ 1.}}\]
\[\boxed{\mathbf{1.}}\]
\[23\ 300 - 3000 = 20\ 300\]
\[Ответ:число\ 20\ 300.\]
\[\boxed{\mathbf{2.}}\]
\[4300 + 670 = 4970\]
\[Ответ:уменьшаемое\ 4970.\]
\[\boxed{\mathbf{3.}}\]
\[3\ ч\ 45\ мин + 2\ ч\ 15\ мин =\]
\[= 5\ ч\ 60\ мин = 6\ ч\]
\[Ответ:6\ ч.\]
\[\boxed{\mathbf{4.}}\]
\[x - 20 = 40 \cdot 2\]
\[x - 20 = 80\]
\[x = 80 + 20\]
\[x = 100\]
\[Ответ:x = 100.\]
\[\boxed{\mathbf{5.}}\]
\[777\ :1 - 77 = 777 - 77 = 700\]
\[Ответ:число\ 700.\]
\[\boxed{\mathbf{6.}}\]
\[x\ :7 = 5080 - 5000\]
\[x\ :7 = 80\]
\[x = 80 \cdot 7\]
\[x = 560\]
\[Ответ:в\ окошке\ число\ 560.\]
\[\boxed{\mathbf{7.}}\]
\[\boxed{\mathbf{8.}}\]
\[\boxed{\mathbf{9.}}\]
\[60 \cdot (9 - 6\ :3) = 420\]