**Solution: **

According to the given statement, both Sonia and Ravi move in the same direction, and at the same time.

Here, the method to find the time when they will be meeting again at the starting point is LCM of 18 and 12.

Therefore, LCM(18, 12) = 2 × 3 × 3 × 2 = 36

Hence, Sonia and Ravi will meet again at the starting point after 36 minutes.