A bubble-point feed of 5 mol% A in B is to be distilled to give a distillate containing 35 mol% A and a bottoms containing 0.2 mol%. The column has a partial reboiler and a partial condenser. If a = 6, calculate the following algebraically: 

(a) The minimum number of equilibrium stages; 

(b) The minimum boilup ratio V / B; 

(c) The actual number of stages for a boilup ratio equal to 1.2 times the minimum