Final answer:
The inequality is 20 < x ≤ 200, where x represents the number of tickets sold.
Step-by-step explanation:
To write the given scenario as an inequality, we can let x represent the number of tickets sold. The train will only run if more than 20 tickets are sold, so the inequality is x > 20. However, there is also a maximum limit of 200 tickets that can be sold, so the inequality is x ≤ 200. Therefore, the combined inequality is 20 < x ≤ 200. This means that the number of tickets sold must be greater than 20, but less than or equal to 200.