Ask a professional musician to teach you what the parallel 85th degree and the reverse 85th degree mean.
parallel 5,8 degrees means that only two voices are parallel, that is, from 5 degrees or 8 degrees, the same direction goes to another 5 degrees or 8 degrees. In addition, there are 5 or 8 degrees hidden, that is, two voices (any interval relationship) develop in the same direction to 5 or 8, which is not allowed in some cases. The reverse is the reverse. You can understand the acoustics book at first sight, but it hurts to master this part of knowledge.