Assume that the demand for apples is characterized by the linear equation QaD = 6PaPb, where Pa is the price of apples and Pb is the price of pears. Assume that the supply for apples is characterized by the linear equation QaS = Pa.

1. Assume that-for some reason-the price of pears is equal to 2, that is, Pb = 2. Write down the system of linear equations that characterizes the equilibrium in the market for apples and solve for the equilibrium price, Pa , and the equilibrium quantity, Qa .

1. Assume now that the demand for pears is given by QbD = 4 Pa Pb. Moreover, let the supply of pears be given by QbS = Pb. Write down the system of linear equations that characterizes simultaneously the equilibrium in the market for apples and for pears, and solve for the equilibrium prices, Pa , Pb , and the equilibrium quantities, Qa , Qb .