SOLUTION: Hi, I am havig problems with miceconomics..demand and supply the problem is : suppose the equation for demand can be expressed as P=30-2Q. The equation for supply can be exp

Click here to see ALL problems on Coordinate-system

Question 324940: Hi,
I am havig problems with miceconomics..demand and supply
the problem is :
suppose the equation for demand can be expressed as P=30-2Q. The equation for supply can be expressed as P=2Q. Find the equilbrium price and quantity . Be able to illustrate the graph that illustrate your answer
Answer by jessica43(140) (Show Source):
You can put this solution on YOUR website!
The main thing you need to know for this problem is that equilibrium occurs where demand equals supply. At this point, both supply and demand have the same price and quantity. This means that you need to set your demand equation equal to your supply equation to find the equilibrium price and quantity:
30 - 2Q = 2Q
30 = 4Q
7.5 = Q
So the equilibrium quantity is 7.5.
Now plug this value into either equation to solve for P (I will use the supply equation, but you should get the same answer if you use the demand equation)
P = 2Q
P = 2(7.5)
P = 15
So the equilibrium price is $15.
This means that when we draw the graph, the two equations will intersect at (7.5, 15) (with price on the y-axis and quantity on the x-axis. This intersection is the equilibrium point.