Ace company has determined that when they set their memory card price at Ksh800 per piece, the quantity demanded is 8000 per week. However, due to high competition by their competitors the demand drops to zero when they raise the memory card price to Ksh1200. Due to their own costs of production they cannot sell the memory cards at a price that is Ksh200 or lower but when the bulk buyers are willing to buy at Ksh400 per memory card, the manufacturer will make available 5000 units per week. The relationship between price and demand, price and supply is known to be linear.
Required:
i. Find the demand equation

ii. Find the supply equation

iii. Find the equilibrium quantity and price