Hello everyone. My first post here.

I have this problem I am trying to work through, please.

Free market. The equations S=5000+200x and D=9500-100x express the supply S and the

demand D, respectively, for a popular compact disc brand in terms of its price x (in dollars).

a) Graph the equations on the same coordinate system.

b) What happens to the supply as the price increases?

c) What happens to the demand as the price increases?

d) The price at which supply and demand are equal is called the equilibrium price. What is the equilibrium

price?

I have already figured out 'd)' as x = 15. I reached this conclusion by:

Since S=5000+200x and D=9500-100x

5000+200x=9500-100x

5000+200x+100x=9500

5000+300x=9500

300x=4500

X=15

I still need to figure out a, b, and c. I know I can use a slope-intercept to figure out the graph using the equation of y=mx+b. This is where I start losing it.

I know that: x = 15. I know the slope-intercept formula is y=mx+b.

Using S=5000+200x, D=9500-100x I would assume these would represent x,y. So, would I assume x=8000, y=8000 and graph them as 8000,8000? So then I would start the problem out as 8000=m(8000)+b?

Your help with the remaining letters is much appreciated.