To find out how many servings Frank can make with 85 tablespoons when each serving is 2 1/2 tablespoons, you need to divide the total tablespoons by the tablespoons per serving.
First, convert 2 1/2 tablespoons to an improper fraction: \[ 2 \frac{1}{2} = \frac{5}{2} \]
Now, divide the total tablespoons by the serving size: \[ \text{Number of servings} = \frac{85}{\frac{5}{2}} \]
To divide by a fraction, multiply by its reciprocal: \[ \frac{85}{\frac{5}{2}} = 85 \times \frac{2}{5} = \frac{85 \times 2}{5} = \frac{170}{5} = 34 \]
Therefore, Frank can make 34 servings of salad dressing.