A two-stage air compressor with perfect intercooling takes in air at 1 bar and 27 °C. The law of compression in both stages is pv^{1.3} = constant, and the air is delivered at 9 bar. Taking R = 0.287 kJ/kg·K and c_{p} = 1.005 kJ/kg·K, calculate per kg of air (a) the minimum work done and (b) the heat rejected to the intercooler (answers in kJ/kg).