Question

Kim borrowed $400 from her parents to purchase a new cell phone. The table represents Kim's repayment schedule. Which inequality states the domain of the relation?

Answer 1

The domain tells you about the independent variable, number of payments made. So the inequality should be smallest number of payments made ≤ variable representing payments ≤ largest number of payments made. The smallest number of payments is 0 and the largest is 8, so you'll have
0≤variable≤8

Answer 2

The answer is  {0 ≤ x ≤ 8} I took a test with this question and got it right.