Correct. In the equation $\displaystyle{\log}_{{{b}}}{x}={y}\usepackage{cmbright}\Huge\$ , b is the base and y is the exponent. So $\displaystyle{{4}}^{{3}}={64}\usepackage{cmbright}\Huge\$ is equivalent to $\displaystyle{\log}_{{{4}}}{64}={3}\usepackage{cmbright}\Huge\$ . Therefore, b stands for 4.