Answer:
6 times.
Step-by-step explanation:
Since she served 3 salads that contain 2/3 cup of blueberries each, and her measuring cup only holds 1/3 cup, she'll have to measure the blueberries 6 times in total, doing 2 measurements per salad (2 x 1/3 = 2/3). Since 2 x 1/3 cup is 2/3 cup, and there are 3 salads in total (multiply 2 measurements by 3 salads), this means she measures the blueberries 6 times.