There are four numbers, and their average is 5. If one of the numbers 1 is changed to 9, what is the sum of these four numbers now?
有四个数，它们的平均数是5，把其中一个数1改为9，那么现在这四个数的和是多少
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

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

<result>28</result>