There are three poker cards, which are 5 of clubs, 7 of hearts and 2 of spades. Two cards are randomly drawn from the three. What is the probability that the difference between them is 2?
有三张扑克牌，分别是梅花5，红桃7和黑桃2，从三张中任意抽出2张，它们的差是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>