Maths...Maths...!! (急!!!!!!!)

Let X be the original selling price of the shoes.
Two weeks ago, Jacky saved 40% of the selling price = 0.4X
Last week, he saved 80% of the rest = (1-0.4X)*0.8 = 0.48X
This week, the shoes are on sale at a 10% discount,
therefore, the discounted price is 0.9X.
Jacky still owes $12, so : 0.4X+0.48X = 0.9X - 12
　　　　　　　　　　　　　　0.02X = 12
　　　　　　　　　　　　　　　　X = 600
The original selling price of the shoes is $600

英文中學嗎?這些英文Math題先翻譯成中文就會明白和較易了~
1.) Jacky計劃買一雙鞋子。 在二個星期以前，他節省了鞋子的 40% 銷售價格。 上星期，他節省了 80% 的其餘者。 這星期，鞋子 10% 優惠中，但是他仍然虧欠＄12 。ask鞋子的最初銷售價格.

let n be the original selling price of the shoes

n+12=n+n*40%+n*80%+n*10%
...


很難~自己再想想吧~(被打)

2006-12-19 21:28:15 補充：
Let n be the original selling price of the shoes0.4X+0.8(0.6X)=0.9X-12 0.4X+0.48X=0.9X-12 -0.02X=-12 X=$600

Let X be the original selling price of the shoes

0.4X+0.8(0.6X)=0.9X-12
0.4X+0.48X=0.9X-12
-0.02X=-12
X=$600