Count Rows between events

[tw2024]

I have been trying to figure out the solution for this issue for quite some time and cannot find the expected solution. I would really appreciate any assistance to the proper way to approach this problem. Thank you!

For every Type "a" I would like a count of Type "b" that occurs before the next Type "a"

So the resulting table would look like this:

1/11/2023 a 1

1/20/2023 a 4

4/4/2023 a 3

6/12/2023 a 6

[ThxAlot · Accepted solution]