To find out how many teammates Vera can serve, we start by determining the total amount of servings available. Vera has 4 bags of nuts and each serving is \( \frac{1}{3} \) of a bag.
First, we calculate the total number of servings:
\[ \text{Total servings} = \text{Total bags} \div \text{Serving size} = 4 \text{ bags} \div \frac{1}{3} \text{ bag/serving} \]
Dividing by a fraction is the same as multiplying by its reciprocal:
\[ \text{Total servings} = 4 \times 3 = 12 \]
So, Vera can serve 12 teammates.