There are two kinds of colored balls, red and yellow, in a bag. If the probability of touching the red ball is (2/3), how many yellow balls should be put in 6 red balls.
一个袋子里有红、黄两种彩球，要使摸到红球的可能性是(2/3)，应放入6个红球，多少个黄球．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 6</gadget>
<output>4</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">2 / (2/3)</gadget>
<output>3</output>

<result>3</result>