數學問題!!!(急!!!~~)

以下是徵收率:
差餉:5%
物業稅16%
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物業稅是課稅年度該代價收入的八成淨金額(即是「應評稅淨值」)將被課"物業稅"
(http://zh.wikipedia.org/w/index.php?title=%E7%89%A9%E6%A5%AD%E7%A8%85&variant=zh-tw)
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1.根據下列各全年租金收入,求各物業業主應繳的物業稅。
(i)$90000
代價收入的八成淨金額
=$90,000*0.8
=$72,000
物業稅
= $72,000*0.16
=$11,520

(ii)$144000
淨金額
=$144,000*0.80
=$115,2000
物業稅
=$115,2000*0.16
=$18,432

問題(3) 請看 http://hk.knowledge.yahoo.com/question/?qid=7007102100981&r=w

4.李先生在2004/2005年度應繳的薪俸稅是$10400。他的太太是一名家庭主婦,他們育有一名女兒,且需供養年逾六十歲的同住媽媽。若李先生選擇合併評稅,求他該年度的平均月薪。

Mr. Lee's total deductions are
$200,000 for married couple
$ 30,000 for his daughter
$ 30,000 for his mother
An extra $30,000 for his mother living in the same quarters (同住)
Total deductions=$290,000

Tax paid on first 30,000 taxable income at 2% = $600
Tax paid on next 30,000 taxable income at 8% = $2,400
Tax paid on next 30,000 taxable income at 14% = $4,200
Total tax for first $90,000 taxable income=$7,200
Total tax paid=$10,400
Tax paid at 20% = $10,400-$7,200=$3,200
Taxable income at 20%=$3,200/.2=$16,000

Mr. Lee's total annual income
= 290,000 + 30,000 + 30,000 + 30,000 + 16,000
=$396,000
Average monthly income=$396,000/12=$33,000

2007-10-23 11:51:19 補充：
#3:Tax on first 30000 taxable income = $600Tax on remainder (<30000) at 8%=$1000-$600=$400 Total taxable income=$30000+$400/0.08=$35,000