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counting and probability junior
Problem
The eighth grade class at Lincoln Middle School has students. Each student takes a math class or a foreign language class or both. There are eighth graders taking a math class, and there are eighth graders taking a foreign language class. How many eighth graders take only a math class and not a foreign language class?
(A)
(B)
(C)
(D)
Solution
Let be the number of students taking both a math and a foreign language class. By P-I-E, we get = . Solving gives us . But we want the number of students taking only a math class, which is .
Final answer
D