AMC 8 2022 Problem 5
AMC8 2022 年第 5 题
方程与不等式★★☆☆☆
Anna and Bella are celebrating their birthdays together. Five years ago, when Bella turned 6 years old, she received a newborn kitten as a birthday present. Today the sum of the ages of the two children and the kitten is 30 years. How many years older than Bella is Anna?
nna 和 Bella 正在一起庆祝她们的生日。五年前，当 Bella 到 6 岁的时候，她收到了一只新生的小猫作为生日礼物。今天，两个孩子与小猫的年龄之和是 30 岁。问 Anna 比 Bella 大多少岁？
- A.1
- B.2
- C.3
- D.4
- E.5
正确答案 · Correct Answer
C
解析 · Solution
Solution 1
Five years ago, Bella was 6 years old, and the kitten was 0 years old. Today, Bella is 11 years old, and the kitten is 5 years old. It follows that Anna is 30-11-5=14 years old. Therefore, Anna is 14-11=3 years older than Bella.
We assume that a)the current age of Anna = a b) the current age of Bella = b b-5=6 Thus, b = 11 Kitten = 5 (as the it got it 5 years ago) Since the total age of kitten and girls = 30, then a = 30-(11+5) =30 - 16 =14 years. BUT THIS IS NOT THE FINAL ANSWER!!! a-b = 14-11 = 3 = option C
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