Assume the universal set $\,\mathcal U = \{1, 2, 3, 4, 5, 6, 7, 8\}$. If $A = \{1, 2, 4, 6, 7\}, B = \{1, 2, 4, 6\}$ and $C = \{1, 3, 4, 7\}$, what is $\overline{A}⊕\overline{B ⊕ C}$ ?
What does is a universal set? And what is the difference between not having the overline above the letters?
Overline means complement: $$\overline{A}=\mathcal{U} \setminus A = \{3,5,8\}.$$