The extracurricular interest group carried out activities. There were 18 people in attendance, 1 person on sick leave, and 1 person on personal leave. What is the attendance rate of this activity?
课外兴趣小组开展活动，有18人出勤，病假1人，事假1人，这次活动的出勤率是多少．
<gadget id="calculator">18 + 1 + 1</gadget>
<output>20</output>

<gadget id="calculator">18 / 20</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(9/10) * 1</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>