There are 45 students in the first class of the sixth grade, and 80% of the students passed the long jump test at the end of the last semester. How many people failed.
六年级一班有学生45人，上学期期末跳远测验有80%的同学及格．不及格的有多少人．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">45 * (4/5)</gadget>
<output>36</output>

<gadget id="calculator">45 - 36</gadget>
<output>9</output>

<result>9</result>