Do I still need blank lines before and after the linear system even if they are itemized items as in this exercise?
Do they have to be aligned as I transcribed them?
Where should the closing Nemeth indicator be placed? Is it OK the way I placed it (or on the line above since this is a spatial arrangement)? I usually place it on a separate line after a plank line. But sometimes, the exercise ends on line 24 or 25 and I don’t want to move the whole problem to a new braille page
First, yes, you do need blank lines around systems of equations, even if they are itemized.
Your transcription (including alignment) is readable and practical as far as I can tell.
Technically, the transcription attached to this message follows the Guidance for Transcription Using the Nemeth Code within UEB Contexts more closely, because it places in cell 1 the opening Nemeth Code indicator that will not fit on a line with text preceding spatial material, and it places on a line by itself in cell 1 after a blank line the Nemeth Code terminator following spatial material.