1) А

- 8,4 ÷ ( - 0,7 ) = - 84 ÷ ( - 7 ) = 12

2) В

-0,752 ÷ х = 0,4

х = - 0,752 ÷ 0,4

х = - 7,52 ÷ 4

х = - 1,88

3)

[tex] - \frac{14}{15} \div \frac{2}{3} = - \frac{14 \times 3}{15 \times 2} = - \frac{7}{5} = - 1 \frac{2}{5} = - 1.4[/tex]

[tex] - 2 \frac{2}{3} \div ( - 1 \frac{7}{9} ) = \frac{8 \times 9}{3 \times 16} = \frac{3}{2} = 1 \frac{1}{2} = 1.5[/tex]

4)

[tex] - 2 \frac{1}{7} \div 0.25 - 1.9 \div ( - 0.1) - \frac{20}{21} \div ( - 1 \frac{2}{3} ) = 11\\ 1) \: - 2 \frac{1}{7} \div 0.25 = - \frac{15 \times 4}{7} = \\ - \frac{60}{7} = - 8 \frac{4}{7} \\ 2) \: - 1.9 \div ( - 0.1) = 19 \\ 3) \: - \frac{20}{21} \div ( - 1 \frac{2}{3} ) = \frac{20 \times 3}{21 \times 5} = \frac{4}{7} \\ 4) \: - 8 \frac{4}{7} + 19 + \frac{4}{7} = 19 - 8 = 11[/tex]

5)

[tex]0.7y -1.6y - 0.4y = 0.65 \\ 0.7y - 2y = 0.65 \\ - 1.3y = 0.65 \\ y = 0.65 \div ( - 1.3) \\ y = 6.5 \div ( - 1.3) \\ y = - 0.5[/tex]