The supply and demand functions for a good are respectively QS = 4P - 12 and QD = 60 - 4P + 4I, with I representing income, P the market price, QS the quantity supplied, and QD the quantity demanded.

a) If I = 10, determine

i) The equilibrium price;

ii) The equilibrium quantity.

b) Suppose the income increases to I = 14. Determine

i) The quantity demanded at the initial equilibrium price;

ii) The equilibrium price;

iii) The equilibrium quantity.