There are 5 white balls and 2 red balls in a box, if one is randomly drawn, what is the probability of drawing a white ball?
盒子里有5个白球和2个红球，任意摸出一个，摸出白球的可能性是多少．
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<result>5/7 = around 0.714286</result>