There are four numbers whose average is 5. If one of the numbers 1 is changed to 9, what is the average of them?
有四个数，它们的平均数是5．把其中一个数1改为9，那么它们的平均数变成了多少
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 + 8</gadget>
<output>28</output>

<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<result>7</result>