If 300 trees are planted, 30 of them did not survive. What is the survival rate?
植树300棵，没成活的有30棵，成活率为多少．
<gadget id="calculator">300 - 30</gadget>
<output>270</output>

<gadget id="calculator">270 / 300</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>