Subtract the 3 dates from different tables

[game1]

Hello,

I have Table2[dateBefore], Table1[dateBegin] and Table1[dateEnd].

So, I need to subtract the 3 dates, so I can have the result in DAYS:  so something like Table2[dateBefore] - Table1[dateEnd] - Table1[dateBegin] 

So, I create a new coloumn call DatesDiff = DATEDIFF(Table2[dateBefore], Table1[dateBegin], DAY) + DATEDIFF(Table2[dateBefore], Table1[dateEnd], DAY)

But the new coloumn call DatesDiff is create in Table1, so I can have acces to Table2[dateBefore].

How can I do if I want to subtract column from differents tables?  I need to have an ID common to the 2 tables to do that?

Can I do that using join?

Please, give complete answer.

[wdx223_Daniel]

if all the IDs in those tables are unique, you can try to add a new step in table1

NewStep=Table.AddColumn(Table1,"DateDiff",each let a=Table2{[ID=[ID]]}?[dateBefore]? in a=null then null else Duration.Days(a-[dateEnd]-[dateBegin]))