There are 40 students in the 6th grade. 25% of them wear glasses and 40% of them wear contact lenses. How many students do not wear any vision assistance wear?
Let's be accurate as possible and think first.
14
There are 40 x 25% = 10 students who wear glasses.

There are 40 x 40% = 16 students who wear contact lenses.

There are 10 + 16 = 26 students who wear vision assistance.

There are 40 - 26 = 14 students who do not wear any vision assistance wear.

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So, the answer is 14