Answer: 2,620 meatballs.
Explanation:
Initially, Harold had 150 meatballs. Sarah ate 30 of them, so there are 150 - 30 = 120 meatballs left. The waiter then brought 2,500 more meatballs. Therefore, the total number of meatballs now is 120 + 2,500 = 2,620 meatballs.