# Change of Base Rule

## Reference > Algebra: Common Logarithms

 DescriptionThe Change of Base Rule states that:$$\log_{b}{x}=\frac{\log_{a}{x}}{\log_{a}{b}}$$
 Examples$\frac{\log_{b}{x}}{\log_{b}{a}}$1 Use Change of Base Rule: $$\log_{b}{x}=\frac{\log_{a}{x}}{\log_{a}{b}}$$$\log_{a}{x}$Donelog(a,x)