Difficult Task - Cumulative but Net Difference

Dear Community,

Let me explain the problem.

1st : We have Data from Hotel Reservations

2nd: We want to Sum Net Difference of reservations and cancellations (Reservations - Cancellations)

3rd : Reservations should be calculated with System Date when they add in system reservation

4th : Cancellation should be calculated with Cancelation Date when they cancel it.

5th : Visual this difference as cummulative For example : 1st day : 100 reservations 50 cancellations = net 50 2nd day : 70 reservations 20 cancellation = 50 +(70-20) = 100 3rd day : 10 reservations 70 cancellations = 100(last day total) + (10-70) = 40

So we will have at the end a diagram with "System Date" (maybe) that each day will have total information per day.

Any Solution on that ? 

Thanks in advance