Frank is making salad dressing for a large party. If a serving is 2 1/2 tablespoons how many servings can he make with 85 tablespoons?

To find out how many servings Frank can make, we divide the total amount of tablespoons by the tablespoons per serving: 85 tablespoons / 2 1/2 tablespoons/serving = <<85/2.5=34>>34 servings. Answer: \boxed{34}.