You may have chosen this expression because one of the addends seemed equal to the sum, but the addend is negative while the sum is positive. The identity property says 0 $\displaystyle+\usepackage{cmbright}\Huge\$ any number $\displaystyle=\usepackage{cmbright}\Huge\$ that number. The correct answer is $\displaystyle{0}+{\left(-{8.2}\right)}=-{8.2}\usepackage{cmbright}\Huge\$ .