I believe the slope is -1
Answer:
Avery needs to pay $14.84
Step-by-step explanation:
When there's a tax we need to sum the original value of the product with the tax's value. To find the amount of money Avery needs to pay in taxes we can apply a rule of three as shown below:

Where "x" is the tax value, and $14 represents 100%, since it's the value used to calculate the tax. We have:

The value to be paid is the product value plus the tax, therefore:

Avery needs to pay $14.84
For some unknown reason, Brainly won't post my answer as it assumes the answer has inappropriate words or a link.
So, I added the answer in the attached image.
Kindly check it.
I got 28.93095228, I hope this is the answer