Listen All Rights Reserved for Dr. Ibrahim Abou-Saad: If in the automobile markets we know that two SUV brands, Z and X, are substitutes. Suppose that the supply of X decreases and, at the same time, the supply of the Z increases. Other things being equal, what would be the expectations for the change in the equilibrium quantities at the two markets? The equilibrium quantity of X will increase and the equilibrium quantity of Z will decrease. The equilibrium quantity of Z will increase and the equilibrium quantity of X will remain the same. The equilibrium quantity of Z will increase and the equilibrium quantity of X will decrease. The equilibrium quantity of X will increase and the equilibrium quantity of Z will remain the same