A Brayton cycle uses argon as the working substance. At the beginning of compression, the temperature is 335 K and the pressure is 480 kPa. The compression process is adiabatic with discharge conditions of 645 K and 1930 kPa. The argon is heated and enters the turbine at 1390 K and 1930 kPa and expands adiabatically to 890 K and 490 kPa. Determine a) the compressor efficency; b) the turbine efficiency; c) the thermal efficiency.