Answer:
The difference is 30%
Step-by-step explanation:
To find the percent decrease, start by finding the difference in costs.
42.54 - 29.78 = 12.76
Now divide that amount by the original cost.
12.76/42.54 = 30%
We see that the slope of this line is so we plug this and the point into the point-slope form (note that there's nothing special about the point I picked; you can choose any point on the line):
This rearranges to the slope-intercept form
Answer: The constant of proportionality is 5 because the equation would be y=kx but instead of k it has 5.