# Supply: Qs = 4P - 80 Demand: Qd = 100 - 2P What Is The Equilibrium Price And Quantity? Calculate Consumer Surplus At Equilibrium.

In order to find the market equilibrium set Qd= Qs which is equal to

100 - 2P = 4P - 80

Subtracting 100 from both side you will get
- 2P = 4P - 80 -100
- 2P = 4p -180

Now subtracting 4P from both sides you will get
- 2P - 4P = -180
-6p = - 180

Dividing both sides by -6 you will get

-6/-6 P = -180/-6

If P= 30 then

Qs = 4(30)-80
=120-80

Qd = 100 - 2(30)
=100 - 60
= 40

Qs = Qd which is 40 = 40

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1. Suppose that the royalties received by an author for writing a college text are set at a rate of 15 percent of the publisher’s total revenue.

A. Demonstrate graphically that this creates an inherent conflict between the interests of a profit-maximizing publisher and those of a royalty-maximizing author.  [Hint:  Draw a graph with optimal price and output for both the publisher and author.]

b. As a student consumer, whose interests would you like to see prevail?
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Qd=10-3p

Qs=2+p

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