For each set of individual demand functions, calculate the market demand function and draw both the individuals' and market demand on 1 graph.
a) 300 people, each has demand function P = -15x + 90. (Note: you need only graph 1 individual demand and the market demand)
b) 2 people: person 1 has demand x = -P + 75, person 2 has demand x = -3P + 135.