Four number cards with 2, 3, 7, and 8 written on them respectively. Take any two of them and form a 2-digit integer. What is the average value of all the integers formed by this method?
四张数字卡片，分别写有2、3、7、8．从其中任取两张拼成2位整数，请问用此法拼成的所有整数的平均值是多少．
<gadget id="calculator">2 + 3 + 7 + 8</gadget>
<output>20</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">11 / 12</gadget>
<output>11/12 = around 0.916667</output>

<gadget id="calculator">20 * 3 * (11/12)</gadget>
<output>55</output>

<result>55</result>