$(1)$
\[\begin{equation}
\left \{
\begin{array}{l}
p_s=1.0 \,\rm{MPa} \\
h' = 762.68 \,\rm{kJ/kg} &
h' ' = 2777.12\,\rm{kJ/kg}\\
s' =2.13843 \,\rm{kJ/(kg \cdot K)} &
s' ' =6.58498 \,\rm{kJ/(kg \cdot K)}
\end{array}
\right.
\end{equation}\]
\[
\begin{align}
h
&=(1-x)h' + xh' ' \\
&=0.2 \times 762.68+0.8 \times 2777.12 \\
\therefore
&=2374.232 \ \rm{kJ/kg}
\end{align}
\]
$(2)$
\[
\begin{align}
s
&=(1-x)s'+ xs' '\\
&=0.2 \times 2.13843 + 0.8 \times 6.58498 \\
&=5.69567 \ \rm{kJ/(kg\cdot K)}
\end{align}
\]
