Start with $\displaystyle{7}+{\left(-{36}\right)}\usepackage{cmbright}\Huge\$ . Since $\displaystyle{36}-{7}={29}\usepackage{cmbright}\Huge\$ , and $\displaystyle{36}>{7}\usepackage{cmbright}\Huge\$ , $\displaystyle{7}+{\left(-{36}\right)}=-{29}\usepackage{cmbright}\Huge\$ . Next find $\displaystyle-{29}-{12}=-{29}+{\left(-{12}\right)}\usepackage{cmbright}\Huge\$ . Since $\displaystyle{29}+{12}={41}\usepackage{cmbright}\Huge\$ , and both numbers are negative, $\displaystyle-{29}+{\left(-{12}\right)}=-{41}\usepackage{cmbright}\Huge\$ . Finally subtract $\displaystyle-{41}-{\left(-{41}\right)}=-{41}+{41}={0}\usepackage{cmbright}\Huge\$ .