Answer
$\Delta T=-92.9°F$
$\Delta u =-2.53\ Btu/lbm$
Work Step by Step
From table A-6:
Inlet ($P_1=120\ psia$, sat. liquid): $T_1=90.49°F,\ u_1=0.41.49\ Btu/lbm,\ h_1=41.79\ Btu/lbm$
Outlet ($P_2=20\ psia, h_2=h_1$): $T_1=-2.43°F,\ u_2=38.96\ Btu/lbm$
Hence:
$\Delta T=-92.9°F$
$\Delta u =-2.53\ Btu/lbm$
