數學問題~~~(2)

1同2題,題目不清,
題2 你寫$305係兩间一樣?
有冇英文版?
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我有意回答,我會每日加改

2007-02-01 21:19:19 補充：
Let [x] be the A bank money you putLet [y] be the B bank money you put∴5%[x]+6%[y]=$305(given)......﹫1(公式1)because $155 is only for half year ∴one yeay is $310--------對單位4%[x]+7%[y]=$310(given)......﹫2(公式2)5%[x]+6%[y]=$305 @1 (公式1)4%[x]+7%[y]=$310 @2(公式2)

2007-02-01 21:19:38 補充：
in @1 5%[x] 6%[y]=$305 5%[x]=305-6%[y] [x]={305-6%[y]}÷5% @3compair @3 to @24%[x] 7%[y]=$310經過7部運算後,[y]=$3000 @4 compair @4 to @15%[x] 6%[y]=$305[x]=$2500∴[x]=$2500 [y]=$3000 ---------------------------------------覆數XXXXXX由於時间關係,,,覆數係正確的

2007-02-01 21:20:38 補充：
#########################比D时间我解Q1

2007-02-01 21:27:53 補充：
原來下面有有人答左Q1,,,我覆過數,係正確的...^^-----------------------------------------------------------------------如你對的Q2解答不清楚或想轉中文,請say出黎

一個3位數的個.十.百的數字之和為13~百位數是10位數的2倍少2

如把3位數的百位同十位對換~所得的2位數比原先3位數少297

求原來的3位數,this question seems have some problem,
first we let the unit digit be x
the tens digit be y
the 百位 be z
from the first sentence we have the equation
x+y+z=13
no problem with this equation
and from the second equation we have
z=2y-2
still no problem with this equation
but from the third sentence, we have
(100z+10y+x)-(10y+z)=297
which is not correct
let me explain it:Assume that the no.is 123
so when we reverse the position of the tens digit and the 百位
we get a two-digits no. 21
and then we - the two no.
123-21=102
did you notice that the tens digit is 0?
so it's impossible for the tens digit to be 9

2007-02-01 17:19:28 補充：
還有一點就是我就當你"如把3位數的百位同十位對換~所得的2位數比原先3位數少297"這句中的所得的2位數是錯的,應該是3位數的話,也是不對的,因為只是十位和百位對換,對個位沒有影響,所以兩個數相減後個位應是0,所以不應得到297的