If 40 trees are planted and 4 die, what is the survival rate?
种40棵树，死了4棵，成活率是多少．
<gadget id="calculator">40 - 4</gadget>
<output>36</output>

<gadget id="calculator">36 / 40</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>