The students planted trees, 450 trees survived, and 50 trees did not survive. What is the survival rate?
同学们植树，活了450棵，没活的50棵，成活率是多少．
<gadget id="calculator">450 + 50</gadget>
<output>500</output>

<gadget id="calculator">450 / 500</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>