1987 AMC 8 第 15 题

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15.

一个促销广告写着:“按原价买三条轮胎,第四条轮胎只要 $3。”Sam 在促销中花 $240 买了一套四条轮胎。一条轮胎的原价是多少?

A sale ad read: "Buy three tires at the regular price and get the fourth tire for $3." Sam paid $240 for a set of four tires at the sale. What was the regular price of one tire?

$59.25

$60

$70

$79

$80

答案:D
知识点:逆推法
难度评级:860
解答:

三条原价轮胎共花 $240$3=$237\$240 - \$3 = \$237

所以一条轮胎的原价是 $2373=$79\dfrac{\$237}{3} = \$79

所以正确答案是 D

The three regular-price tires cost $240$3=$237.\$240 - \$3 = \$237.

So one tire costs $2373=$79.\dfrac{\$237}{3} = \$79.

Thus, the correct answer is D .

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其他年份的第 15 题

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