1. The problem statement, all variables and given/known data in photo 391 , we can see that the levelling work is back to the same point , which is TBM1 . so , the adjustment of correction is (Bs -Fs ) / number of points ... But in 392-394 , the levelling work is from a known point to a different point ..... I'm wondering that is the adjustment correct ? It's given that adjustment = end closure / number of TP ... 2. Relevant equations 3. The attempt at a solution In the table provided , we can see that there are only 2 TP , why the author divided by 3 for the case in 392-394 ?