Multiply both sides by \(21\).
\[\frac{4}{7}\times 21=x\]
Use this rule: \(\frac{a}{b} \times c=\frac{ac}{b}\).
\[\frac{4\times 21}{7}=x\]
Simplify \(4\times 21\) to \(84\).
\[\frac{84}{7}=x\]
Simplify \(\frac{84}{7}\) to \(12\).
\[12=x\]
Switch sides.
\[x=12\]
x=12
