You may have incorrectly added $\displaystyle-{30}+{\left(-{25}\right)}\usepackage{cmbright}\Huge\$ to get $\displaystyle-{5}\usepackage{cmbright}\Huge\$ , and then correctly added $\displaystyle-{5}+{72}\usepackage{cmbright}\Huge\$ . To add two negative numbers, you must add their absolute values ( $\displaystyle{30}+{25}\usepackage{cmbright}\Huge\$ ), and place a negative sign on the result.