Or, it looks like TT just wants to separate the interest expense from the 'other', non-interest expense, since the lines shown the calculation are all associated with interest expense, whereas line 54 col.F is a tally of lines 25-53. So I'm guessing it wants the difference between that tally and the sum of the lines listed in parentheses (39-43), which in my case is zero. That's my best guess. How can we make something so simple, so complicated.
