I need to consult with other committee members to give you a full answer.
But I can start with:
BANA's "Provisional Guidance on Transcribing Mathematics in UEB" (Approved May 2019) says (in part),
For displayed mathematical expressions, use blank lines preceding and following; and indent 2 cells from the runover position of the material to which they apply. –second paragraph under 3. General format
That means the spatial addition problem in your example should have its left margin at cell 5.
Now I'm going to ask others about placement of the numeric passage indicator and terminator.