[問題]GWD01-30(31套版)

[Ricky1120]

30.Joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy?
(1)She bought $4.40 worth of stamps
(2)She bought an equal number of 0.15 stamps and $0.29 stamps

這題我選C 但答案是D 請各位大大幫忙了!

[steven]

這題答案應該有錯 答案是A
0.15跟0.29互質 所以用A就可以解出買0.15跟0.29的都是10張

[Ricky1120]

0.15X+0.29Y=4.4
請問為何互質就帶的出X=Y=10?
是要一個一個帶嗎?

[steven]

我只能說這題是特例了 只有這唯一解 所以在算時要小心點 有時間的話 最好驗算看看