There are 55 students in Class 1 of Sixth Form, and the excellent rate in the mid-term exam in mathematics is 80%. How many people are not excellent.
六1班有学生55人，数学期中考试成绩优秀率80%，没有达到优秀的有多少人．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">55 * (1/5)</gadget>
<output>11</output>

<result>11</result>