Решебник по математике 5 класс Мерзляк ФГОС Решаем устно параграф 41

\[\boxed{\mathbf{1.\ }}\]

\[1)\ \frac{1}{4}\ т = 1000\ :4 = 250\ кг\]

\[2)\ \frac{1}{5}\ т = 1000\ :5 = 200\ кг\]

\[3)\ \frac{3}{10}\ т = 1000\ :10 \cdot 3 = 300\ кг\]

\[4)\ \frac{2}{5}\ ц = 100\ :5 \cdot 2 = 40\ кг\]

\[5)\ \frac{3}{25}\ ц = 100\ :25 \cdot 3 = 12\ кг\]

\[6)\ \frac{7}{20}\ ц = 100\ :20 \cdot 7 = 35\ кг\]

\[\boxed{\mathbf{2.\ }}\]

\[x > \frac{1}{10}\]

\[x = \frac{1}{9};\frac{1}{8};\frac{1}{7};\frac{1}{6};\frac{1}{5};\frac{1}{4};\frac{1}{3};\frac{1}{2}.\]

\[\boxed{\mathbf{3.\ }}\]

\[1)\ 6x = 636\]

\[x = 636\ :6\]

\[x = 106.\]

\[2)\ 84\ :x = 7\]

\[x = 84\ :7\]

\[x = 12.\]

\[3)\ x \cdot 43 = 43\]

\[x = 43\ :43\]

\[x = 1.\]

\[\boxed{\mathbf{4.\ }}\]

\[1)\ 13a + 13b = 13 \cdot (a + b) =\]

\[= 13 \cdot 10 = 130.\]

\[2)\ 45m - 45n = 45 \cdot (m - n) =\]

\[= 45 \cdot 20 = 900.\]