Answer:
$900
Explanation:
South's deductible casualty loss = $900
Fair market value before the flood                18500
Fair market value after the flood                  (2000)
Decline in FMV Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 16500
Cost basis                                     20000
Lesser of basis or decline in FMV Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 16500
Minus: Insurance proceeds                      (13000)
Net loss                                      3500
Minus: $100 Floor                              (100)
10% of AGI Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (2500)
Deductible Loss                               900