Step-by-step explanation:
First step:
Calculate a slope.
The formula of a slope:

The slope-intercept form of an equation of a line:

m - slope
b - y-intercept
We have the points (5, -4) and (-1, 8). Substitute:

Put the value of the slope and the coordinates of the point (5, -4) to the equation of a line:

<em>add 10 to both sides</em>

Finally:

CD = 13
6x - 5 = 4x + 1, combine like terms to get
2x = 6, divide 6 by 2
x=3, plug it in...
CD= 4(3)+1, which is 12 + 1
CD = 13
I would use the equation
24 + 8x = 112
let x = the amount of CDs she bought.
Hope this helps!!
The x goes diagonal from they y variable