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题库 / Prep2007E2-DS-69
At the bakery, Lew spent a total of $6.00 for one kind of cupcake and one kind of doughnut. How many doughnuts did he buy?
(1) The price of 2 doughnuts was $0.10 less than the price of 3 cupcakes.
(2) The average (arithmetic mean) price of 1 doughnut and 1 cupcake was $0.35.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
还没有题目讲解（毕出老师会陆续发布对官方考题的解读，请保持关注）。
(1)(2)together 能算出两个各自的价格，题目问的是6$买了几个
能算出各自的价格，但是6刀能买的组合不止一种
题目没读清楚，题干没说买了几个D和几个C,求的是买了几个D。。
0.4x+0.3y=6 ,有两组整数解，少算一步
是4组整数解，晕
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设c有x个，d有y个，求y是多少（1）2d=3c-0.1，不能求出y（2）d+c=0.7，不能求出y（1)(2)一起也不能知道y，所以E
你这里少想了两步……
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0.4x+0.3y=6 有整数解呀 x=6 和 y=12的时候 是因为不止一个整数解？
还有 x=9,y=8; x=12,y=4
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with 1 and 2, we could count cupcake and donghut's price. but how many of donghut 0.4x+0.3y=6? no integer solution.