in AMT form,part II,i am not able to understand calculation for line 32

i.e 15971...can someone help plz..

from wiley software

James Gellert, a self-employed carpenter (social security number 353-21-3251), is married and itemized deductions when filing a joint income tax return for 2009 with his wife Nancy.

Compute the Gellerts’ alternative minimum tax for 2009 by completing Form 6251 Alternative Minimum Tax—Individuals.

Adjusted gross income (Form 1040 line 38)	$135,000
Taxable income before personal exemptions (Form 1040 line 41)	87,500
Personal exemptions (2 x $3,650)	7,300
Regular tax liability (Form 1040 line 44)	12,744
Interest income from State of Ohio general obligation bonds	4,000
Interest income from specified private activity bonds purchased in 2008	15,000
Depreciation on 5-year MACRS property using the 200% declining balance method (depreciation would have been $18,000 using the 150% declining balance method, and would have been $12,000 if the straight-line method had been used)	24,000
Itemized deductions:
Medical expenses (after 7.5% of AGI floor)	5,000
State income taxes	6,000
Real estate taxes	12,000
Home mortgage interest on loan to acquire principal residence	13,000
Home equity mortgage interest (loan proceeds were used to purchase an auto)	1,500
Charitable contributions	9,000
Miscellaneous deductions (after 2% of AGI floor)	1,000