After the 15% discount, Maria pays 85% of the cost. That cost is the sum of the fixed cost and the variable (per visit) cost.
... (updated cost) = 0.85×($150 +$30×a)
... (updated cost) = 127.50 +25.50a . . . . in dollars
Sorry i cant see the picture so well
Answer:




The absolute difference is:

If we find the % of change respect the before case we have this:

So then is a big change.
Step-by-step explanation:
The subindex B is for the before case and the subindex A is for the after case
Before case (with 500)
For this case we have the following dataset:
500 200 250 275 300
We can calculate the mean with the following formula:

And the sample deviation with the following formula:

After case (With -500 instead of 500)
For this case we have the following dataset:
-500 200 250 275 300
We can calculate the mean with the following formula:

And the sample deviation with the following formula:

And as we can see we have a significant change between the two values for the two cases.
The absolute difference is:

If we find the % of change respect the before case we have this:

So then is a big change.
No he is wrong because 75% more time would be spent doing homework
I would use what times 6 = 36 because 6*6+36