Question

Camilla 原来拥有的蓝莓味软糖数量是樱桃味软糖数量的两倍。她每种各吃了十颗后，蓝莓味软糖数量变成樱桃味软糖数量的三倍。她原来有多少颗蓝莓味软糖？

Camilla had twice as many blueberry jelly beans as cherry jelly beans. After eating 10 pieces of each kind, she now has three times as many blueberry jelly beans as cherry jelly beans. How many blueberry jelly beans did she originally have?

$10$

$20$

$30$

$40$

$50$

答案：D

知识点：方程组一次方程

难度评级：900

解答：

设原来樱桃味有 $c$ 颗，蓝莓味有 $b$ 颗。

吃软糖前后的条件分别给出 $b = 2c$ $b-10=3(c-10)$

所以 $2c-10 = 3c-30$ $c=20.$ $b = 2\cdot 20=40.$

所以正确答案是 D。

Let the number of cherry jelly beans be $c$ and let the number of blueberry jelly beans be $b.$

Then, we know $b = 2c$ $b-10=3(c-10)$ from the first and second statements respectively.

Therefore, $2c-10 = 3c-30$ $c=20.$ This means that $b = 2\cdot 20=40.$

Thus, the correct answer is D .

2017 AMC 10B 第 5 题

答案：D

难度评级：900

解答：

其他年份的第 5 题