calculating the sum of a certain column that satisfy a certain condition

[TAZ95]

Hello, I am trying calculate the commission of a certain trainer based on the number of sessions the trainer does.

Each session belongs to a pack and packs are in two type. Each session the trainer get a base commission of 85 or 95 depending on the type of pack it belongs to. However, this base commission is calculated only after 15 sessions. for example ( assuming the type of session is the same and base commission is 85, total session is 20. The trainer will get only 85+85+85+85+85). The date is split into two main tables. 

I have calculated a column (base commission) that will able to identify if the commission is 85 for EACH PACK.

the scond Table have the information about the trainers and pack the session belongs to

Eventually, I am going to filter trainer information. once I filter a certain trainer from table 2, the packs will filter in table 1. Therefour ill be able to find the commission related to that trainer. But how to calculate the commission without considering the first 15 sessions. 

I hope its clear.

Thanks

[lbendlin]

Please provide sanitized sample data that fully covers your issue.
https://community.powerbi.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-Forum/ba-...
Please show the expected outcome based on the sample data you provided.

https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523