The school planted a batch of 200 trees, but 20 failed to survive. What is the survival rate of this batch of trees?
学校种了一批树有200棵，结果有20棵没成活，这批树的成活率是多少．
<gadget id="calculator">200 - 20</gadget>
<output>180</output>

<gadget id="calculator">180 / 200</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>