A research firm provided a firm's marketing manager with the estimated of the demand and supply functions for its product X as;

Qd= 780-4Px-2Pm+Pn-0.1Y+0.8A, Qd is greater than 0

Qs= -300+4Px-1.5Pl

where Px is the price of the commodity X; Pm is the price of the commodity M=$15;Pn is the price of commodity N=$50; Yis the income=$40000; A is the advertising expenditure =$10000; Pl is the average price of unskilled labor=$80

a. Find the equilibrium price and quantity

b. Graph both demand and supply

c. Which product in the demand function is a substitute for product X?

d. If income falls by $5000, find the new equilibrium price and quantity . Will equilibrium price and quantity increase or decrease? Explain