If you get butterflies in your stomach every time you have to use CALCUATE or FILTER functions in your DAX then stick around, as I will try to give you some tools that will hopefully bring that anxiety to manageable levels.
This is not a short video, unfortunately. I could not cut it short because if you are not comfortable with these functions, you are probably having issues with gaps in some your understanding of several important concepts in Power BI. Therefore, I am thoroughly walking over all of the things that you should have a good grasp of before you are ready to use Calculate() and Filter().
Then we are going to go through several iteration of Calculate() and Filter() as we make our calculation more and more complex, but, again, I am taking baby steps with each iteration as I want to make sure that I am not losing you in the process.