\[\boxed{\mathbf{1067\ (1067)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[420\ :100 \cdot 15 = 4,2 \cdot 15 =\]
\[= 63\ (га) - засеяли\ рожью.\]
\[Ответ:63\ га.\]
\[\boxed{\mathbf{1067}\mathbf{.}\mathbf{\ }}\]
\[1)\ \left( \frac{1}{3} \right)^{5} = \frac{1}{3^{5}} = \frac{1}{243}\]
\[2)\ \left( \frac{3}{7} \right)^{3} = \frac{3^{3}}{7^{3}} = \frac{27}{343}\]
\[3)\ \left( 1\frac{2}{5} \right)^{2} = \left( \frac{7}{5} \right)^{2} = \frac{7^{2}}{5^{2}} = \frac{49}{25} =\]
\[= 1\frac{24}{25}\]
\[4)\ \left( 3\frac{1}{4} \right)^{2} = \left( \frac{13}{4} \right)^{2} = \frac{13^{2}}{4^{2}} =\]
\[= \frac{169}{16} = 10\frac{9}{16}\]