Помогите пожалуйста,обведённые номераplease help

Здравствуйте!

1)
$\frac{1}{24} x - ( \frac{1}{3} x + ( - \frac{2}{9} x - ( - \frac{4}{9} x + ( - \frac{5}{12} x)))) = \\ \\ = \frac{1}{24} x - ( \frac{1}{3} x + ( - \frac{2}{9} x - ( - \frac{16}{36} x - \frac{15}{36} x))) = \\ \\ = \frac{1}{24} x - ( \frac{1}{3} x + ( - \frac{8}{36} x + \frac{31}{36} x)) = \\ \\ \frac{1}{24} x - ( \frac{12}{36} x + \frac{23}{36} x) = \\ \\ = \frac{1}{24} x - \frac{35}{36} x = \\ \\ = \frac{3}{72} x - \frac{70}{72} x = \\ \\ = - \frac{67}{72} x$

2)
$8.4 - 2.7(7b - 1.3(10 - 11b)) - 15.7b = \\ = 8.4 - 2.7(7b - 13 + 14.3b) - 15.7b = \\ = 8.4 - 18.9b + 35.1 - 38.61b - 15.7b = \\ = 43.5 - 73.21b$
3)
$- \frac{3}{40} ( - 2a - ( \frac{1}{3} + 12y)) - \frac{1}{7} ( - 14a - (7 + \frac{2}{3} a)) = \\ \\ = - \frac{3}{40} ( - 2a - \frac{1}{3} - 12y) - \frac{1}{7} ( - 14a - 7 - \frac{2}{3} a) = \\ \\ = \frac{3}{20} a + \frac{1}{40} + 0.9y + 2a + 1 + \frac{2}{21} a= \\ \\ = 2 \frac{103}{420} a + 1.025 + 0.9y$

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