1 2/13*(3/7x-5/6)=2,5

[latex]1 \frac{2}{13}*( \frac{3}{7}x- \frac{5}{6})=2,5 \\ \\ \frac{15}{13}*( \frac{3}{7}x- \frac{5}{6})= \frac{5}{2} \\ \\ \frac{45}{91} x=\frac{5}{2}+\frac{75}{78} \\ \\ \frac{45}{91} x=\frac{39*5+75}{78}=\frac{270}{78}= \frac{135}{39}= \frac{45}{13} \\ \\ x=\frac{45}{13} : \frac{45}{91}=\frac{45}{13}*\frac{91}{45}=7[/latex]

1[latex] \frac{2}{13} [/latex]* ([latex] \frac{3}{7}x- \frac{5}{6} [/latex])= 2,5 [latex] \frac{3}{7}x- \frac{5}{6} [/latex]= 2,5: 1[latex] \frac{2}{13} [/latex]= [latex] \frac{5}{2} [/latex] : [latex] \frac{15}{13} [/latex]= [latex] \frac{5}{2} [/latex] * [latex] \frac{13}{15} [/latex] [latex] \frac{3}{7}x- \frac{5}{6} [/latex]= 2[latex] \frac{1}{6} [/latex] [latex] \frac{3}{7}x= \frac{5}{6} [/latex] + 2[latex] \frac{1}{6} [/latex] [latex] \frac{3}{7} x[/latex]= 3 x= 3: [latex] \frac{3}{7} [/latex]= 3* [latex] \frac{7}{3} [/latex] x= 7 Ответ: x= 7.