There are 45 students in the fifth grade. 80% of the students passed the long jump test at the end of the last semester. How many students failed?
五年级有学生45人，上学期期末跳远测试有80%的同学及格，不及格的同学有多少人？
<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">45 * (1/5)</gadget>
<output>9</output>

<result>9</result>