What is the value of x in the equation 7/8x=5/6?

$x = \frac{20}{21}$
First, divide both sides by $\frac{7}{8}$ to get $x = \frac{\frac{5}{6}}{\frac{7}{8}}$. Next, simplify the right side to get $x = \frac{5}{6} \cdot \frac{8}{7} = \frac{40}{42}$, which equals $\frac{20}{21}$.