let's firstly convert the mixed fractions to improper fractions and then add.
[tex]\bf \stackrel{mixed}{2\frac{7}{10}}\implies \cfrac{2\cdot 10+7}{10}\implies \stackrel{improper}{\cfrac{27}{10}}~\hfill \stackrel{mixed}{8\frac{1}{2}}\implies \cfrac{8\cdot 2+1}{2}\stackrel{improper}{\cfrac{17}{2}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{27}{10}+\cfrac{17}{2}\implies \stackrel{\textit{using an LCD of 10}}{\cfrac{(1)27+(5)17}{10}}\implies \cfrac{27+85}{10}\implies \cfrac{112}{10}\implies \cfrac{56}{5}\implies 11\frac{1}{5}[/tex]
