20% of the students in a school are myopic. After correction, the number of myopic students decreases by 50%. After follow-up treatment for myopic students, the number of myopic students decreases by another 20%. What percentage of the normal vision rate of this school is now?
一所学校有20%的学生近视，经过矫正后，近视的学生减少50%，对近视的学生跟踪治疗后，近视的学生又减少20%，现在这所学校视力正常率达到百分之几？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/5) * (1/2) * (4/5)</gadget>
<output>2/25 = around 0.08</output>

<gadget id="calculator">1 - (2/25)</gadget>
<output>23/25 = around 0.92</output>

<result>23/25 = around 0.92</result>