This is what you get when you apply these two properties in this order: $\displaystyle{\left(\frac{{2}}{{7}}+\frac{{1}}{{3}}\right)}+\frac{{3}}{{4}}=\frac{{2}}{{7}}+{\left(\frac{{1}}{{3}}+\frac{{3}}{{4}}\right)}\usepackage{cmbright}\Huge\$ or $\displaystyle\frac{{3}}{{4}}+{\left(\frac{{1}}{{3}}+\frac{{2}}{{7}}\right)}={\left(\frac{{3}}{{4}}+\frac{{1}}{{3}}\right)}+\frac{{2}}{{7}}\usepackage{cmbright}\Huge\$