From the formula above, you see that your slope would be the $12.
Step-by-step explanation:
So, from this problem the base rate is the y-intercept because it is fixed. The slope of the is the additional fee because it's changing by the number of albums sold. Below is the equation that should have been created using the slope intercept formula.
220 + 12x = 644
You will need the slope intercept form, y = mx + b
