10)8-7+2

10) $$\begin{array}{rcl}8\frac{2}{31}-7\frac{17}{31}+2\frac{30}{31}&=&1\frac{2}{31}+2\frac{30}{31}=3\frac{32}{31}=4\frac{1}{31}\end{array}$$

Ответ: $$4\frac{1}{31}$$