You added the absolute values of all the fractions. Instead, first add the two negative numbers: add $\displaystyle{2}\frac{{1}}{{3}}+\frac{{5}}{{6}}\usepackage{cmbright}\Huge\$ and put a negative sign in front. Now you will have $\displaystyle{7}\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ plus a negative number. Find the difference of their absolute values, then figure out if the answer is positive or negative.