How do create a measure for a table using a sum calculation from another table?

[BBHouston]

For example, let's say I have two tables. The first one is 'Dates':

School	Date
School A	10/15
School A	10/22
School B	10/11
School B	10/18
School C	10/12
School C	10/19

The second one is 'Enrollment':

School	Enrollment Date
School A	10/11
School A	10/12
School A	10/12
School A	10/13
School A	10/21
School B	10/9
School B	10/9
School B	10/10
School B	10/17
School B	10/18
School C	10/11
School C	10/12
School C	10/19
School C	10/19

I want an output that generates the number of 'Enrollment' rows BEFORE OR THE DAY OF the specific school and date in 'Dates' table, so it should look something like this:

School	Date	Cumulative
School A	10/15	4
School A	10/22	5
School B	10/11	3
School B	10/18	5
School C	10/12	2
School C	10/19	4

Is there a measure I can write where this table visual is possible?

[amitchandak · Accepted solution]

@BBHouston , new column in table 1

countx(filter(table2, Table2[School]= table1[School] && table2[Enrollment Date] <= Table1[Date]),Table2[School])

[BBHouston]

@amitchandakIt worked!! Thank you thank you! 🙂