True, the suggestion we make about reading the math without the words does work here (2.5 + 2.5 DOES = 5). I would be surprised to see this example in a textbook because it is incomplete. I would expect to see 2.5 pounds + 2.5 pounds = 5 pounds, in which case the words definitely are part of the equality.
I agree with you that the problem you show can be interpreted either way. Here is where the transcriber would need to make a decision and then apply it consistently throughout the transcription.
Lindy