A heat engine carries one mole of an ideal diatomic gas around the cyclic process shown in the $P$–$V$ diagram: AB is an isochoric step from $T_A = 300\,\text{K}$ to $T_B = 600\,\text{K}$; BC is an isobaric expansion to $T_C = 400\,\text{K}$; CA is an isobaric compression back to state A. The amount of heat added in process AB and heat removed in process CA are: