\[\boxed{\mathbf{Вариант\ 1.}}\]
\[\boxed{\mathbf{1.}}\]
\[1)\ Увеличь\ в\ 4\ раза:\]
\[7 \cdot 4 = 28\]
\[9 \cdot 4 = 36\]
\[5 \cdot 4 = 20\]
\[8 \cdot 4 = 32\]
\[6 \cdot 4 = 24\]
\[2)\ Уменьши\ в\ 3\ раза:\]
\[18\ :3 = 6\]
\[24\ :3 = 8\]
\[21\ :3 = 7\]
\[27\ :3 = 9\]
\[12\ :3 = 4\]
\[\boxed{\mathbf{2.}}\]
\[1)\ \rightarrow 8\ :4 = 2\]
\[2)\ \rightarrow 8 - 4 = 4\]
\[3)\ \rightarrow 8 \cdot 4 = 32\]
\[\boxed{\mathbf{3.}}\]
\[21\ :7 + 1 = 4\]
\[18\ :9 + 1 = 3\]