Suppose we postulate a linear demand curve Q_D = a - bP and observe, through supply shifts, two points on the demand curve.At point A, P_A = 2 and Q_DA = 6.At point B, P_B = 4 and Q_DB = 2.What is the choke price for this demand curve?Please round and write the answer to one cent, for example $2.43 or $0.56.Use a minus sign to indicate if the number is negative.