Question

Срочно даю 67 баллов!!!!!!!

Answer 1

1)

$8.4 \times ( - 5.7) = - 47.88$

$( - 5 \frac{3}{5} ) \times ( - 1 \frac{4}{21} ) = \frac{28 \times 25}{5 \times 21} = \frac{4 \times 5}{1 \times 3} = \frac{20}{3} = 6 \frac{2}{3}$

$22.23 \div ( - 0.9) = 222.3 \div ( - 9) = - 24.7$

$- 28.98 \div ( - 14) = 2.07$

2)

$- 4.2x \times ( - 6y) = 25.2xy$

$8m + 5p - 13m - p = 4p - 5m$

$k - (17 - k) + ( - k + 30) = k - 17 + k - k + 30 = k + 13$

$- 6(4 + a) + 8(a - 6) = - 24 - 6a + 8a - 48 = 2a - 72$

3)

$( - 1.42 - ( - 3.22)) \div( - 0.8) + ( - 6) \times ( - 0.7) =1.95 \\ - 1.42 - ( - 3.22) = - 1.42 + 3.22 = 1.8 \\ 1.8 \div ( - 0.8) = - 2.25 \\ ( - 6) \times ( - 0.7) = 4.2 \\ - 2.25 + 4.2 = 1.95$

4)

$5( - 1.4a + 3) - (1 - 2.5a) - 4(0.8a + 3) = - 7a + 15 - 1 + 2.5a - 3.2a - 12 = 2 - 7.7a = 2 - 7.7 \times \frac{5}{7} = 2 - \frac{77 \times 5}{10 \times 7} = 2 - \frac{55}{10} = 2 - 5.5 = - 3.5$