At Euler Middle School, 198 students voted on two issues in a school referendum with the following results: 149 voted in favor of the first issue and 119 voted in favor of the second issue. If there were exactly 29 students who voted against both issues, how many students voted in favor of both issues?
A. 49
B. 70
C. 79
D. 99
E. 149

Inclusion-exclusion principle中文
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Worked solution

1. 2015 AMC 8 官方解析

容斥原理：共 198 人，设两个都支持的人数为 xx，149+119−x+29=198149 + 119 - x + 29 = 198，x=99x = 99，有 99 个同学两个方案都支持。

Answer

D. 99

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