Question

在一场有十道题的数学竞赛中，学生答对一题得 $5$ 分，答错一题扣 $2$ 分。Olivia 回答了所有题，得分为 $29$ 。她答对了多少题？

In a mathematics contest with ten problems, a student gains $5$ points for a correct answer and loses $2$ points for an incorrect answer. If Olivia answered every problem and her score was $29,$ how many correct answers did she have?

$5$

$6$

$7$

$8$

$9$

答案：C

知识点：一次方程

难度评级：1290

解答：

设 $x$ 为答对题数。那么她答错了 $10 - x$ 题。

她的总分为 $5x - 2(10 - x) = 7x - 20.$

该值等于 $29$ ，解得 $7x - 20 = 29$ $x = 7.$

所以正确答案是 C。

Let $x$ be the number of correct answers. Then she answered $10 - x$ questions incorrectly.

This gives her a total score of $5x - 2(10 - x) = 7x - 20.$

We know that this equals $29,$ and solving yields $7x - 20 = 29$ $x = 7.$

Thus, C is the correct answer.

2002 AMC 8 第 17 题

答案：C

难度评级：1290

解答：

其他年份的第 17 题