After putting 6 red balls and 3 yellow balls in a pocket that are identical except for their color, what is the probability that a ball is drawn out of it to be a red ball?
在口袋里放入除了颜色外完全相同的6个红球和3个黄球后，现在从中摸出1个球，是红色球的可能性是多少．
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<gadget id="calculator">6 / 9</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>