Calculated row in Matrix based on another Matrix

I am encountering an issue in Power BI where I am unable to display custom row titles in the Rows section of a matrix table.

Looks easy to achieve but i'm really struggling with this one....

I want to have a similar table (Ratio Matrix):

Then what I have achieved so far:

i have created a New Measure (not sure if this is the right method)

Ratio_1 =
CALCULATE (
    SUM ( '2023'[ETP] ),
    '2023'[Schools] IN {"School 6", "School 4"}
) / SUM ( '2023'[ETP] )P] )