You may have found the value of $\displaystyle{\log}_{{{4}}}{4}\usepackage{cmbright}\Huge\$ to be 1, which is correct, but you did not use the product property, $\displaystyle{\log}_{{b}}{\left({M}{N}\right)}={\log}_{{b}}{M}+{\log}_{{b}}{N}\usepackage{cmbright}\Huge\$ . Use the product property and then simplify. The correct answer is $\displaystyle{1}+{\log}_{{{4}}}{c}\usepackage{cmbright}\Huge\$ .