Investors & landlords

Thanks!  Prior depreciation on the home being used by TT is $35,825 (It is an airbnb rental and it was not always rented out for the whole year).  How does the calculation work taking into account the prior depreciation?  If I reduce the basis by the $35,825, my remaining (adjusted?) basis is $134,275.  I have tried dividing that by several different amounts, nothing gives me the amount Turbo Tax is using : $6,537:

20.5:  (27.5-6) (6: prior years in service): $6,550

21.5:  $6,245.35

20: (27.5-7.5) (first year is .5?): $6,713

Note: Turbotax has the year of depreciation as 8

My tax accountant just used the Total basis/27.5, was she incorrect?  Is there an IRS document/section that defines how the prior depreciation is used and how it impacts current depreciation?