Since sales tax goes after the discount, it would be 3 dollars and 20 cents. Taking 50 dollars and 20% is discounted (50*.2), which would be 10 dollars taken off. It would be 40 dollars shoes and then you apply sales tax by multiplying 40 by .08, giving you the amount of tax paid.
The answer is D
You just need to subtract term 1 (5) from term 2 (10) to find the answer, and the common difference between each sequential term is 5
Answer: x+6>84
6 greater than x ---> x+6
greater than 84-------> >84
Hopefully this helped!