this is Math for business and finance

1. The demand and supply of two interdependent commodities are given by QD1 = 25-2P1 + P2 QD2 = 30 + P1 - 3P2 Qs1 = - 9 + 3P, Qs2 = - 4+ 4P2 a) Determine the equilibrium prices and the quantities of this two-commodity model. b) Are the goods substitutable or complementary ? 2. Given the demand and supply equations : P = - 20p + 38 P = 1/3 Qs + 17 a) Find the equilibrium price and quantity. b) Tax of 10% is imposed, find the new equilibrium price and quantity. c) Find the extra pay by the supplier