There are five numbers, and the average is 7. If one of the numbers is changed to 1, then the average of the five numbers is 6. What should be the changed number?
有五个数，平均数是7，如果把其中的一个数改为1，那么五个数的平均数为6，这个改动的数原来应该是多少．
<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<gadget id="calculator">35 - 30</gadget>
<output>5</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>