\(\displaystyle{\left(\frac{{5}}{{8}}\right)}+{\left(\frac{{11}}{{12}}\right)}=\)

Least Common Multiplier of 8,12: 24 \(\displaystyle={\left(\frac{{15}}{{24}}\right)}+{\left(\frac{{22}}{{24}}\right)}\)

Since the denominators are equal, combine the fractions: \(\left(\frac{a}{c}\right)+-\left(\frac{b}{c}\right)=\frac{a+b}{c} =\frac{15+22}{24}=\frac{37}{24}\)