Randomly draw 2 of the three number cards 5, 7, 2, what is the probability that the difference is 2
从三张数字卡片5，7，2中任意抽出2张，差是2的可能性是多少
<gadget id="calculator">7 - 5</gadget>
<output>2</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>