## Precalculus (6th Edition) Blitzer

$\log_{4}64=3$
$\log_{b}x=y$ is equivalent to $b^{y}=x$ --- $\log_{4}64=y$ is equivalent to $4^{y}=64.$ Since $4^{3}=64$, it follows that $y=3$, so $\log_{4}64=3$