need help on dax

I have a table with sales and earnings columns, and i put those in the matrix where sales are in rows and the sum of earnings is in the values section. However, when I drag a "Earning point" measure into the values section of the matrix, I don't get the desired result. I have a slicer outside of the disconnected table of which is sales data, I need a solution such that if I select 297  in the slicer (which is a sales value from the disconnected table), it should display the maximum value of earnings between 297 and 300 in the matrix, specifically in front of 297 and 300 only. Similarly, if I select 350, it should show the maximum earnings value between 300 and 350 in front of 300 and 350 only (300 is fixed point). rest should be the blank

provide me the dax so i can put in the measure