= \overline{b} + \overline{a} + b \cdot \left( \overline{c} + \overline{a} \right) = \left( \overline{b} + b \cdot \overline{c} \right) + \overline{a} \cdot \left( 1 + b \right) = \overline{b} + \overline{c} + \overline{a} =