Do not forget to subtract 1 from the first mixed number when you regroup. You need to subtract $\displaystyle{8}\frac{{5}}{{3}}-{6}\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ , not $\displaystyle{9}\frac{{5}}{{3}}-{6}\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ .