\[\boxed{\mathbf{1.}}\]
\[\boxed{\mathbf{2.}}\]
\[\textbf{а)}\ \]
\[Проверка:\]
\[\textbf{б)}\]
\[Проверка:\]
\[\textbf{в)}\ 21\ 028\ 000\ :700 =\]
\[= 210\ 280\ :7 = 30\ 040\]
\[Проверка:\]
\[\boxed{\mathbf{3.}}\]
\[= 19 \cdot 4 - 3 \cdot 10 + 56\ :14 =\]
\[= 76 - 30 + 4 = 50\]
\[\boxed{\mathbf{4.}}\]
\[1)\ (35 - 9)\ :2 = 13\ (ведер) -\]
\[картошки\ выкопал\ Вася.\]
\[2)\ 13 + 9 = 22\ (ведра) - \ \]
\[картошки\ выкопал\ папа.\]
\[Ответ:13\ ведер\ и\ 22\ ведра.\]
\[\boxed{\mathbf{5.}}\]
\[x - 397\ 466 = 8039\]
\[x = 8039 + 397\ 466\]
\[x =\]
\[Проверка:\]
\[405\ 505 - 397\ 466 = 8039\]
\[8039 = 8039.\]
\[\boxed{\mathbf{6.}}\]
\[\textbf{а)}\ (d\ :8) \cdot c\ \ (человек) - можно\ \]
\[разместить\ в\ \text{c\ }лодках.\]
\[\textbf{б)}\ a - (n + n\ :2) - кедровых\ \]
\[шишек.\]
\[\boxed{\mathbf{7.}}\]
\[A = \left\{ 16;32;48;64;80;96 \right\};\]
\[B = \left\{ 20;31;42;53;64;75;86;97;\ldots \right\}\]
\[A \cap B = \left\{ 64 \right\}.\]