You may have rewritten the subtraction as $\displaystyle{36.8}-{\left(-{47.3}\right)}=-{36.8}+{\left(-{47.3}\right)}\usepackage{cmbright}\Huge\$ , thinking you could add the opposite of the first addend. But you should rewrite the subtraction by adding the opposite of the second number: $\displaystyle{36.8}+{47.3}\usepackage{cmbright}\Huge\$ . The correct answer is 84.1