There are 2 red balls and 2 white balls in the bag, what is the probability of touching the red ball
袋子里装了2个红球，2个白球，摸到红球的可能性是多少
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>