middle school preparatory grade student planted 20 trees on Arbor Day last year, and 2 of them did not survive. What is the survival rate?
某中学预备年级学生去年植树节植树20株，其中没有成活的有2株，那么成活率是多少．
<gadget id="calculator">20 - 2</gadget>
<output>18</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>