Математика 6 класс учебник Мерзляк, Полонский ответы – номер 817

х : у = 4 : 9
4y = 9x
y = 9/4x
15z = 22/3y
z = 8/3 ÷ 15 ∙ y = 8/3 ∙ 1/15 ∙ y = 8/45y = 8/45 ∙ 9/4x = (8÷4)∙(9÷9)/(45÷9)∙(4÷4) ∙ x = 2∙1/5∙1 ∙ x = 2/5x
у : z = 15 : 22/3
x + y + z = 219
x + 9/4x + 2/5x = 219
x + 9∙5/4∙5x + 2∙4/5∙4x + 219
x + 45/20x + 8/20x = 219
20/20x + 53/20x = 219
73/20x = 219
x = 219 ÷ 73/20 = 219∙20/73 = 219∙20÷73/73÷73 = 3 ∙ 20 = 60
x = 60
y = 9/4 ∙ 60 = 9∙60÷4/4÷4 = 9 ∙ 15 = 135
y = 135
z = 2/5 ∙ 60 = 2∙60÷5/5÷5 = 2 ∙ 12 = 24
y = 24