作者yourself (你，在做什麽呢？)
看板GMAT
标题[问题] PP2-DS-109
时间Fri Aug 22 18:45:02 2008
这题感觉上答案应该是Ｃ，不过详解上的答案是Ｂ，我看不懂详解上的思路，有好心
人可以指点一下吗？
谢谢。
109.
Marta bought several pencils. If each pencil was either a 23-cent pencil or
a 21-cent pencil, how many 23-cent pencils did Marta buy?
(1) Marta bought a total of 6 pencils.
(2) The total value of the pencils Marta bought was 130 cents.
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【答案】B
【思路】
(2) 2x+ 21(x+y) = 130
x+y =6
x=2, y=4……sufficient
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1F：推 cmchen40:(2) 23x+21y=2x+21(x+y)=130 可有一解 08/22 20:27
2F：推 growthme:这种陷阱，真很容易太开心之下，就大力的踩下去了。 08/22 20:33
3F：→ yourself:是因为刚好只有这个解吗？ 08/22 21:32
4F：→ yourself:而且我有点不太懂改成2x+21(x+y)=130之後要怎麽求x+y，谢 08/22 21:33
5F：推 abib:23x + 21y = 2x + 21(x+y) 是这样吗？ XDDD 08/23 00:07