Решебник по математике 6 класс Виленкин Часть 1, 2 Часть 2. Параграф 6. Координаты на плоскости Задание 18

\[\boxed{\mathbf{6.18}}\]

\[\textbf{а)}\ 21 + 9,7 \cdot (3,4 - 3,7) =\]

\[= 21 + ( - 2,91) = 18,09\]

\[3,4 - 3,7 = - 0,3\]

\[9,7 \cdot ( - 0,3) = - 2,91\ \]

\[40,7 + 4,4 = 45,1\]

\[45,1\ :1,1 = 451\ :11 = 41\]

\[\textbf{в)}\ \left( 0,7 - \frac{7}{20} \right) \cdot 2\frac{2}{9} - 0,4\ :1,8 =\]

\[= \frac{5}{9}\]

\[0,7 - \frac{7}{20} = \frac{7}{10} - \frac{7}{20} = \frac{14}{20} - \frac{7}{20} =\]

\[= \frac{7}{20}\]

\[\frac{7}{20} \cdot 2\frac{2}{9} = \frac{7}{20} \cdot \frac{20}{9} = \frac{7}{9}\]

\[0,4\ :1,8 = \frac{4}{18} = \frac{2}{9}\]

\[\frac{7}{9} - \frac{2}{9} = \frac{5}{9}\ \]

\[\textbf{г)}\ \left( 2,28 - 1\frac{7}{25} \right)\ :\frac{4}{9} - 0,375\ :\frac{1}{6} =\]

\[= 2\frac{1}{4} - 2\frac{1}{4} = 0\]

\[2,28 - 1\frac{7}{25} = 2,28 - 1,28 = 1\]

\[1\ :\frac{4}{9} = 1 \cdot \frac{9}{4} = 2\frac{1}{4}\]

\[0,375\ :\frac{1}{6} = \frac{375}{1000} \cdot 6 = \frac{3}{8} \cdot 6 =\]

\[= \frac{9}{4} = 2\frac{1}{4}\]