It appears that you divided $\displaystyle-{36}\usepackage{cmbright}\Huge\$ by 4 and put the answer over the denominator 5. You need to rewrite the division as multiplication by the reciprocal of the divisor: $\displaystyle-\frac{{36}}{{1}}\cdot\frac{{5}}{{4}}\usepackage{cmbright}\Huge\$ . The correct answer is $\displaystyle-{45}\usepackage{cmbright}\Huge\$ .