Add and Subtracting Time & Date within Defined Ranges

[MichaelRSnow]

Hi, I need some help and I don't know where to start with this one?

I'm trying to build a resource plan, tasks take specific amount of time and I want to add or subtract this time to existing times to calculate the date they would be processed on? My date range would have non working days (Saturdays & Sundays and non working hours, 6pm to 8am), is this possible with excel

i.e. If...
Task 1 was scheduled to complete by 5pm on Fri 5th Jan
Task 2 (which had a dependency on Task 1) takes 2 hours, it would complete at 9am on Mon 8th Jan
Task 3 (which had a dependency on Task 2) take 30 minutes, it would complete at 9.30am on Mon 8th Jan

I can create a annual table with working hours and working days which it can lookup, but don't know where to start with the formula?

Table as per below

DAY	START TIME	FINISH TIME
FRI	05/01/2018 00:09:00	05/01/2018 00:17:00
SAT	06/01/2018 00:00:00	06/01/2018 00:00:00
SUN	07/01/2018 00:00:00	07/01/2018 00:00:00
MON	08/01/2018 00:09:00	08/01/2018 00:17:00

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