Answer
$x=3$
Work Step by Step
"Difference" indicates subtration.
"Of" indicates multiplication.
$3-\frac{2}{7}x =\frac{5}{7}x \longrightarrow$ Translate the sentence into an equation.
$3-\frac{2}{7}x + \frac{2}{7}x=\frac{5}{7}x+\frac{2}{7}x \longrightarrow$ Add $\frac{2}{7}x$ from both sides
$3=x\longrightarrow$ simplify