The diver's depth is represented by $\displaystyle-{128}+{45}\usepackage{cmbright}\Huge\$ . You added the absolute values of the addends. Because the addends have different signs, you must find the difference of their absolute values and give the sum the same sign as the addend with the greater absolute value. The correct answer is $\displaystyle-{83}\usepackage{cmbright}\Huge\$ .