The equation $\displaystyle{{b}}^{{y}}={x}\usepackage{cmbright}\Huge\$ is equivalent to $\displaystyle{\log}_{{{b}}}{x}={y}\usepackage{cmbright}\Huge\$ . When the base of the exponential equation is 9, then $\displaystyle{b}={9}\usepackage{cmbright}\Huge\$ .