Duration of Parked Vehicles

Hello!!

I want to find the duration of vehicles in the parking lot.
Data set is as follows:
From: From survey time
To: To survey Time
Car No. Is licence plate number

Survey was done for every 15 min period (random 15 min Periods) which says if the vehicle was present at the time or not.
Sample data presented here is also mixture of different parking location.

How do i find the parking duration of the vehicle.