Suppose you are given the following supply and demand equations for your company's product, executive fountain pens:

Qd = 12,000 - 2P + 3Py - 5Pn - 2Pk + 4M + 3A

Qs = 8,000 + 4,000P - 7Pm - 3Pw

where:

Qd = quantity demanded of fountain pens

Qs = quantity supplied of fountain pens

P = price per unit of fountain pens

Py = price per unit of pencils

Pn = price per unit of notebooks

Pk = price per bottle of ink

M = consumer income

A = number of units of advertising purchased by the company

Pm = cost of purchasing materials (inputs) for fountain pens

Pw = cost of hiring a worker (wage rate)

a) given the signs of the coefficients in the demand equation, how does the demand for fountain pens react to each variable (i.e., substitutes, complements, normal good, inferior good)? (2 points each)

b) given the signs of the coefficients in the supply equation, how does the supply for fountain pens react to each variable? (2 points each)

c) suppose you are given the following data:

Py = $10

Pn = $15

Pk = $8

M = $20,000

A = 1,000 units

Pm = $2

Pw = $70

Calculate the equilibrium price and quantity for fountain pens. Round the quantity to the nearest whole number and the price to the nearest hundredth (i.e., dollars and cents ($xx.xx))