Answer:
After 30 minutes, they would be located at (4,- 4).
Explanation:
Consider the provide information.
The restaurant rotates clockwise 90° every 15 minutes.
After 30 minutes they rotate 180° clockwise.
After the first 15 minutes, their location can be located at (4, 4) and after the second 15 minutes, their location can be located at (4,-4).
Thus, 30 minutes later, they would be located at (4,- 4).