How to join columns from different tables and insert a calculated column in PowerBI / Power Query

I have 2 tables in Power BI: ITEMS and SUB_ITEMS.

ITEMS is a table of actions to be performed.
SUB_ITEMS is a table of sub actions to be performed, regarding to the main action.
ITEMS has 15 rows.
SUB_ITEMS has 70 rows.

Each action in SUB_ITEMS has a percentage of completion:

sub action 1) 100%
sub action 2) 0%
sub action 3) 0%
sub action 4) 20%
sub action 5) 20%

In this case, the total progress of the main action (ITEMS) should be 28%:

sub action 1) 100% of 20% = 20%
sub action 2) 0% of 20% = 0%
sub action 3) 0% of 20% = 0%
sub action 4) 20% of 20% = 4%
sub action 5) 20% of 20% = 4%
total progress) 20% + 0% + 0% + 4% + 4% = 28%

I created a calculated table that gives me the percentage for each action (eg. 20%).

The percentage for each sub action is already in the table SUB_ITEMS (eg. 100%, 0%, 0%, 20%, 20%).

I need to put the column ITEM_NUMER, from ITEMS, together with SUB_ITEM_NUMBER into a new table, in order to apply the percentage from ITEMS (eg. 20%) over each percentage from the SUB_ITEMS (eg. 100%, 0%, 0%, 20%, 20%).

I don't know how to apply this percentage, once that the measure created to bring the 20% percentage is not available in Power Query, only in Power BI.

I'd appreciate your help.

Thanks in advance.

Solution

Assuming your data looks like this in Powerquery

Then in the ITEMS table, add column .. custom column .. with formula

 = [Percent]*List.Sum(SUB_ITEMS[Percent])