Final answer:
The number -15 is not a solution to the inequality x ≤ -17 because -15 is greater than -17, which does not satisfy the inequality's condition.
Step-by-step explanation:
When evaluating whether a number is a solution to an inequality, we must determine if it makes the inequality true when the number is substituted in place of the variable. For the inequality x ≤ -17, we are checking if -15 is a solution. The inequality x ≤ -17 states that x should be either less than or equal to -17. Since -15 is greater than -17, it does not satisfy the inequality, and therefore, -15 is not a solution to the given inequality x ≤ -17.