Here's the problem:

Problem:Recall that you can use two points on a line to determine an equation for the line. Suppose two points in a coordinate plane have coordinates(x1, y1)and(x2, y2).Alright, I know this is $\displaystyle b = \frac{y1-y2}{x1-x2}$. No problem there.A.Write a formula that gives the slopebof the line containing the two points.

I don't quite remember how to do this. In the end, I got $\displaystyle Y1 = b(x1-x2)+y2$ Please correct me on this.B.Solve the equation for in Part a fory1in terms of the other variables.

This is the part I thought was a brain teaser/tongue twister. What do you do here?C.In your equation from Part b, replace the point with coordinates(x1, y1), with a general point(x, y)on the line. Explain how this equation is now that of a line with slopebthrough the point(x2, y2).

I don't have the equation for C. yet, so I'll wait for help on that first.D.Use your equation from Part c to write the equation of the line that contains the points(8, 12)and has slope-2. What is the y-intercept of this line?