Answer:
11548KJ/kg
10641KJ/kg
Step-by-step explanation:
Stagnation enthalpy:

given:
cp = 1.0 KJ/kg-K
T1 = 25 C +273 = 298 K
V1 = 150 m/s

Answer: 11548 KJ/kg
Using Heat balance for steady-state system:

Qin = 42 MW
W = -100 KW
V2 = 400 m/s
Using the above equation

Answer: 10641 KJ/kg
c) We use cp because the work is done per constant pressure on the system.