急*.1條中1既maths''

2007-11-22 2:09 am
我想問下lee到up緊乜-口-''
xx計劃買鞋..佢2星期前就儲蓄左x鞋售的40% : 上星期他再儲蓄''如''下部分的80%。
this week x鞋以90%出售,,但他還欠 $12 .
THAT X鞋的原價系?

THXXX!
更新1:

佢2星期前就儲蓄左x鞋售的40% 系 :佢2星期前就儲蓄左x鞋售價的40% THAT X鞋的原價系? 系 :咁X鞋既原價系咩?

回答 (3)

2007-11-23 3:10 am
✔ 最佳答案
Let a be the original price of the shoes

40%a + 80%(1 - 40%)a + 12 = 90%x
40%a + 48%a + 12 = 90%x
88%a + 12 = 90%a
2%a=12
a=600

so the original price of the shoes is 600.


Hope can help you!
參考: me
2007-11-22 3:24 am
let x be the original price of the shoes

40%x + 80%(1 - 40%)x + 12 = 90%x
40%x + 48%x + 12 = 90%x
88%x + 12 = 90%x
2%x=12
x=600

so the original price of the shoes is 600
2007-11-22 3:10 am
設鞋的原價=A

90%A = 80%A+$12
90%A-80%A=$12
10%A=$12
A= $120


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