negative time recalculation

[bartvdg]

input	input	formula (arrived on site - driving time)
DRIVING TIME	ARRIVED ON SITE	STARTED DRIVING
1:00	15:00	14:00
3:00	19:30	16:30
18:00	3:00	gives negative number ######## - should be 9:00

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Who can help me solving above?
I calculate the 'started driving time" by subtracting arrival time from driving time.
When negative i don't know how to calculate for correct time?

 

[Yongle]

Date is an integer formatted as a date where
1 = 1 Jan 1900
2 = 2 Jan 1900
43591 = 6 May 2019

Time is a decimal between 0 and 1
0.25 = 6 am
.5 = 12 noon
.75 = 6 pm
0.99653 = 11.55 pm
etc

Time differences
A combination of date and time is required to deal with any situation that may arise
43591.25 = 6pm on 6 May 2109 etc
43592.75 = 6am on 7 May 2109 etc
The difference is .5 = 12 hours

Possible simple workaround
If the total time NEVER exceeds 24 hours, a simple workaround is to amend the formula to add 1 to the number if negative

<a1)*1< html=""></a1)*1<>

 

[Yongle]

I intended to post the worksheet to illustrate
Here it is ...

Excel 2016 (Windows) 32 bit

	A​	B​	C​	D​
1​	Drive	Arrive	Driving time	formula
2​	01:00​	15:00​	14:00​	=(B2-A2)+1*(B2 < A2)
3​	03:00​	19:30​	16:30​	=(B3-A3)+1*(B3 < A3)
4​	18:00​	03:00​	09:00​	=(B4-A4)+1*(B4 < A4)

Sheet: Sheet1

 

[AhoyNC]

Another option (again assuming difference between times will not be greater than 24 hrs.).
Copy formula down as needed.

Excel Workbook
	A	B	C	D
1	Drive	Arrive	Driving time	formula
2	1:00	15:00	14:00	14:00
3	3:00	19:30	16:30	16:30
4	18:00	3:00	9:00	9:00
Sheet