Question 1192880
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A class of 30 students took two quizzes. Sixteen passed the first quiz and 20 passed the second. 
If 4 students failed both quizzes, how many passed both?
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From the condition, 30-16 = 14 failed the first quiz, and

                    30-20 = 10 failed the second quiz,

             while           4 failed both quizes.


Hence,  the number of those who failed at least one quiz is  14 + 10 - 4 = 20.


It means that 30-20 = 10 students passed both quizes.    <U>ANSWER</U>
</pre>

Solved.