Math test

Students wrote a math test. The average number of points obtained by them was 64. Another student wrote this test for 80 points. If the teacher added his result to the original ones, the total average of all students would be 65. How many students originally wrote the test?

Correct answer:

n =  15

Step-by-step explanation:

64n + 80 = 65·(n+1)

64·n + 80 = 65·(n+1)

n = 15

n = 15/1 = 15

n = 15

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