ГДЗ по математике 6 класс Ерина Никольский рабочая тетрадь Часть 1, 2 Часть 1 | Страница 81

\[\mathbf{Страница\ 81.}\]

\[\boxed{\mathbf{9.}}\]

\[\frac{1}{7} = \frac{- 8}{- 56}\]

\[\frac{- 15}{20} = \frac{3}{- 4}\]

\[\frac{- 6}{7} = \frac{30}{- 35}\]

\[\frac{- 18}{- 22} = \frac{9}{11}\]

\[\frac{44}{- 11} = \frac{44}{- 11}\]

\[\frac{- 32}{- 4} = \frac{- 32}{- 4}\]

\[\frac{33}{- 88} = \frac{- 3}{8}\]

\[\boxed{\mathbf{10.}}\]

\[\textbf{а)}\ \left( 152\frac{3}{4} - 148\frac{3}{8} \right) \cdot \frac{3}{10}\ :\frac{1}{5} =\]

\[= 6\frac{9}{16}\]

\[152\frac{6}{8} - 148\frac{3}{8} = 4\frac{3}{8}\]

\[4\frac{3}{8} \cdot \frac{3}{10} = \frac{35}{8} \cdot \frac{3}{10} = \frac{21}{16}\]

\[\frac{21}{16}\ :\frac{1}{5} = \frac{21}{16} \cdot 5 = \frac{105}{16} = 6\frac{9}{16}\]

\[\textbf{б)}\ \left( 85\frac{7}{30} - 83\frac{5}{18} \right)\ :2\frac{2}{3}\ :\frac{1}{25} =\]

\[= 18\frac{1}{3}\]

\[85\frac{21}{90} - 83\frac{25}{90} =\]

\[= 84\frac{111}{90} - 83\frac{25}{90} =\]

\[= 1\frac{86}{90} = 1\frac{43}{45}\]

\[1\frac{43}{45}\ :\frac{8}{3}\ :\frac{1}{25} = \frac{88}{45} \cdot \frac{3}{8} \cdot 25 =\]

\[= \frac{11 \cdot 5}{3} = \frac{55}{3} = 18\frac{1}{3}\]

\[\boxed{\mathbf{11.}}\]

\[\textbf{а)}\ 450 - 350 = 100\ \left( \frac{м}{мин} \right) -\]

\[скорость\ сближения.\]

\[\textbf{б)}\ 22\ :100 = \frac{22}{100} = \frac{11}{50}\ (мин) -\]

\[понадобилось\ бы\ собаке,\ чтобы\ \]

\[догнать\ кота.\]

\[\textbf{в)}\ 350 \cdot \frac{11}{50} = 77\ (м) -\]

\[пробежал\ бы\ кот.\]

\[\textbf{г)}\ 450 \cdot \frac{11}{50} = 99\ (м) -\]

\[пробежала\ бы\ \ собака.\]