Математика 6 класс учебник Виленкин, Жохов 2 часть ответы – номер 5.88

а) 1/27a - (4/9a - 1/3a) = 1/27a - 4/9a + 1/3a = 1/27a - 12/27a + 9/27 = -2/27a;

б) 5/7(7/5a - 7) - 9(21/3a + 5/9) = 5/7 ∙ 7/5a - 5/7 ∙ 7 - 9 ∙ 7/3a - 9 ∙ 5/9 = a - 5 - 21a - 5 = -20a - 10;

в) 4/5(1,5c - 4,5) - 3/9(2,7c - 6,3) = 4/5 ∙ 15/10c - 4/5 ∙ 45/10 - 3/9 ∙ 27/10c + 3/9 ∙ 63/10 = 12/10c - 36/10 - 9/10c + 21/10 = 3/10c - 15/10 = 0,3c - 1,5;

г) 1/9(0,9b - 1,8) -1/2(0,2b - 0,4) = 1/9 ∙ 9/10b - 1/9 ∙ 18/10 - 1/2 ∙ 2/10b + 1/2 ∙ 4/10 = 1/10b - 2/10 - 1/10b + 2/10 = 0.