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? Think carefully first, then make a decision:
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. So, the answer is 14.