Solution:

( Dùng cách đơn giản nhất để thực hiện phép tính sau :$\frac{1}{2}:\frac{2}{7}-\frac{1}{3}:\frac{2}{7}+\frac{5}{6}:\frac{2}{7}$)

$\frac{1}{2}:\frac{2}{7}-\frac{1}{3}:\frac{2}{7}+\frac{5}{6}:\frac{2}{7}$= $\frac{1}{2}\times \frac{7}{2}-\frac{1}{3}\times \frac{7}{2}+\frac{5}{6}\times \frac{7}{2}=\frac{7}{2}\times \left( \frac{1}{2}-\frac{1}{3}+\frac{5}{6} \right)$

= $\frac{7}{2}\times \left( \frac{3}{6}-\frac{2}{6}+\frac{5}{6} \right)=\frac{7}{2}\times 1$ = 7/2