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?
There are 40 x 25% = <<40*25*.01=10>>10 students who wear glasses.
There are 40 x 40% = <<40*40*.01=16>>16 students who wear contact lenses.
There are 10 + 16 = <<10+16=26>>26 students who wear vision assistance.
There are 40 - 26 = <<40-26=14>>14 students who do not wear any vision assistance wear.
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