There are 5 numbers, and their average is 25. If these 5 numbers are arranged in ascending order, the average of the first 3 numbers is 20, and the average of the last 3 numbers is 30. What is the middle number?
有5个数，它们的平均数是25，如果把这5个数从小到大排列，前3个数平均数是20，后3个数的平均数是30，中间数是多少．
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">25 * 5</gadget>
<output>125</output>

<gadget id="calculator">90 - 125</gadget>
<output>-35</output>

<gadget id="calculator">60 + (-35)</gadget>
<output>25</output>

<result>25</result>