Answer
a) $\nu_2=409.9\ m/s$
b) $A_1/A_2=15.65$
Work Step by Step
From table A-13:
Inlet (700 kPa, 120°C): $v_1=0.043358\ m³/kg,\ h_1=358.92\ kJ/kg$
Outlet (400kPa, 30°C): $v_2=0.056796\ m³/kg,\ h_2=275.09\ kJ/kg$
From the energy balance:
$\dot{m}(h_1+\nu_1^2/2)=\dot{m}(h_2+\nu_2^2/2)$
With $\nu_1=20\ m/s$:
$\nu_2=409.9\ m/s$
From the material balance:
$\frac{A_1\nu_1}{v_1}=\frac{A_2\nu_2}{v_2}$
$A_1/A_2=15.65$
