Calculating sum of points, changes to points over past three sprints

I am trying to create a report that only looks back at the past three sprints by team. The report will show the following in a table, but I can not figure where to start. I need to get a table with the following three items in a table. Once I have these calculated members I will be able to do the rest. I am just really struggling with the calculated members.

Sum of Points Committed in past 3 sprints
Sum of Points added after sprint start for past 3 sprints
Sum of Points removed after sprint start for past 3 sprints

Let me know if there are other items that would be useful for me to provide on this, and thank you for any support you can provide.