Question

12/13 × (3/7x-5/6)=2 1/2 нужно найти х

Answer 1

$1 \frac{2}{13} *( \frac{3}{7}x - \frac{5}{6} )=2 \frac{1}{2}; \\ \frac{15}{13} *( \frac{3}{7}x - \frac{5}{6} )=\frac{5}{2}; | \frac{15}{13}: \\ \frac{3}{7}x - \frac{5}{6}=\frac{5}{2}:\frac{15}{13}; \\ \frac{3}{7}x - \frac{5}{6}=\frac{5}{2}*\frac{13}{15}; \\ \frac{3}{7}x - \frac{5}{6}=\frac{13}{6}; \\ \frac{3*6}{42}x - \frac{5*7}{42}=\frac{13*7}{42}; \\ 18x-35=91; \\ 18x=91+35; \\ 18x=126; \\ x=126:18; \\ x=7$