There are three countries in the world: Country A, Country B, and Country C. These countries have the following domestic demand and supply functions for product Y; SA = 30PA, DA = 400 - 10PA; SB = 40PB, DB = 320 - 40Ps; Sc = 40Pc, De = 240 - 40PC, where subscripts denote countries of the corresponding variables. Country A is considering a preferential free trade agreement with country B (sets import tariff equal to 0 for imports from Country B, but continues to set $3 specific tariffs on imports from Country C). Characterize the trade equilibrium of this three-country world under this preferential trade agreement, and briefly explain the welfare effect of this policy for Country A. Assume that rules of origin are strictly applied in answering this question. The world equilibrium price(s) of product Y under this agreement : (PA = PBC= Country A (imports/exports/does not trade) product Y (from/to) ( ) in the amount of ( Country B (imports/exports/does not trade) product Y (from/to) ( ) in the amount of ( Country B (imports/exports/does not trade) product Y (from/to) ( ) in the amount of ( Country C (imports/exports/does not trade) product Y (from/to) ( ) in the amount of ( Country A (gains/loses) from this free trade agreement by the amount of ( ) comparing with the status quo of imposing $3 specific tariffs on all imports. Brief explanation for the welfare effect of this policy for Country A (comparing with the status quo of imposing $3 specific tariffs on all imports)