Task Duration dependant on priorities

[BenRomeril]

[TABLE="width: 500"]
<tbody>[TR]
[TD] Priority
[/TD]
[TD][/TD]
[TD]Start
[/TD]
[TD]Finish
[/TD]
[TD]Duration (days)
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD][/TD]
[TD]=today()
[/TD]
[TD]+10 days
[/TD]
[TD]10
[/TD]
[/TR]
[TR]
[TD]4
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]10
[/TD]
[/TR]
[TR]
[TD]5
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]10
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]10
[/TD]
[/TR]
[TR]
[TD]7
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]10
[/TD]
[/TR]
</tbody>[/TABLE]


Populate Start / Finish columns based on Priority (including blank missing priorities)

 

[BenRomeril]

[TABLE="width: 381"]
<tbody>[TR]
[TD="align: center"]Priority[/TD]
[TD="align: center"][/TD]
[TD="align: center"]Start[/TD]
[TD="align: center"]Finish[/TD]
[TD="align: center"]Duration (days)[/TD]
[/TR]
[TR]
[TD="align: center"]1[/TD]
[TD="align: center"][/TD]
[TD="align: center"]7/05/2019[/TD]
[TD="align: center"]17/05/2019[/TD]
[TD="align: center"]10[/TD]
[/TR]
[TR]
[TD="align: center"]4[/TD]
[TD="align: center"][/TD]
[TD="align: center"]27/05/2019[/TD]
[TD="align: center"]6/06/2019[/TD]
[TD="align: center"]10[/TD]
[/TR]
[TR]
[TD="align: center"]5[/TD]
[TD="align: center"][/TD]
[TD="align: center"]6/06/2019[/TD]
[TD="align: center"] 16/06/2019[/TD]
[TD="align: center"]10[/TD]
[/TR]
[TR]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[/TR]
[TR]
[TD="align: center"]3[/TD]
[TD="align: center"][/TD]
[TD="align: center"]17/05/2019[/TD]
[TD="align: center"]27/05/2019[/TD]
[TD="align: center"]10[/TD]
[/TR]
[TR]
[TD="align: center"]7[/TD]
[TD="align: center"][/TD]
[TD="align: center"]16/06/2019[/TD]
[TD="align: center"]26/06/2019[/TD]
[TD="align: center"]10[/TD]
[/TR]
</tbody>[/TABLE]

Formula to populate as completed here.
Thanks