2019 AMC 8

Complete problem set with solutions and individual problem pages

Problem 11 Medium

The eighth grade class at Lincoln Middle School has 93 students. Each student takes a math class or a foreign language class or both. There are 70 eighth graders taking a math class, and there are 54 eighth graders taking a foreign language class. How many eighth graders take only a math class and not a foreign language class?

  • A.

    16

  • B.

    53

  • C.

    31

  • D.

    39

  • E.

    70

Answer:D

Solution 1

Let x be the number of students taking both a math and a foreign language class.

By P-I-E, we get 70 + 54 - x = 93.

Solving gives us x = 31.

But we want the number of students taking only a math class,

which is 70 - 31 = 39.

\boxed{\textbf{(D)}\ 39}

 

Solution 2

We have 70 + 54 = 124 people taking classes. However, we over-counted the number of people who take both classes. If we subtract the original amount of people who take classes we get that 31 people took the two classes. To find the amount of people who took only math class, we subtract the people who didn't take only one math class, so we get 70 - 31 = \boxed{\textbf{(D)} \, 39}.