You did not find a common denominator for the fractions, and incorrectly attempted to subtract the numerators and denominators. First subtract $\displaystyle{23}\frac{{7}}{{8}}-{10}\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ , using a common denominator of 8. Then compare $\displaystyle{\left|-{23}\frac{{7}}{{8}}\right|}\usepackage{cmbright}\Huge\$ and $\displaystyle{\left|{10}\frac{{3}}{{4}}\right|}\usepackage{cmbright}\Huge\$ to see if the answer is positive or negative.