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