8 white balls and 2 red balls are placed in a box, and one ball is drawn at random, what is the probability that it is a red ball?
在箱子里放入8个白球和2个红球，任意取出一个球，是红球的可能性是多少．
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>