The average of some 3 numbers is the smallest prime number, if one of the numbers is changed to 4, the average becomes 3. What was the original number changed?
某3个数的平均数是最小的质数，如果把其中一个数改为4，平均数变成了3．被改变的数原来是多少？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<result>1</result>