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GWD6-30

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.

Answer: A

My Answer: C

Did I miss something here? The question looks too simple... Pls help!

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请注意,邮票的张数必然是个整数。
It is not only a test! It is Beyond GMAT!
Robert Zhou
http://weibo.com/irobert

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QUOTE:
以下是引用robert在2006-10-15 22:40:00的发言:
请注意,邮票的张数必然是个整数。

嗯,这个很关键

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15x + 29y = 440

x >= 0, y >= 0且为整数,所以y必定能被5整除,
y = 5, 10, 15
很容易算出y=10,x=10是唯一解

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The only thing you missed out is that the number of the $0.15 stamps and that of the $0.29 stamps must be integers.

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