1)2целых1/7:2,5=8,4:7х 2)4,5х:2,7=9:1,8 

[latex]2 \frac{1}{7} : 2,5 = 8,4 : 7x[/latex] [latex] \frac{15}{7} : \frac{25}{10} = 8.4 : 7x [/latex] [latex] \frac{6}{7} = 8.4 : 7x [/latex] [latex]7x = \frac{84}{10} : \frac{6}{7} [/latex] [latex]7x = \frac{7}{5} * 7 [/latex] [latex]7x = \frac{49}{5} [/latex] [latex]x = \frac{49}{5} : 7 [/latex] [latex]x = \frac{7}{5} = 1 \frac{2}{5} = 1.4 [/latex] ========================================== [latex]4.5x : 2.7 = 9 : 1.8[/latex] [latex] \frac{4.5x}{2.7} = \frac{9}{1.8} [/latex] [latex]4.5x * 1.8 = 2.7 * 9[/latex] [latex]4.5 * 1.8 = 24.3[/latex] [latex]4.5x = 24.3 : 1.8[/latex] [latex]4.5x = 13.5[/latex] [latex]x = 13.5 : 4.5[/latex] [latex]x=3[/latex] ===========================================