The average of the numbers A and B is 38.5, and the sum of the three numbers after adding the number C is 110. What is the number C?
甲、乙两数的平均数是38.5，加上丙数后三个数的和是110，丙数是多少．
<gadget id="calculator">38.5 * 2</gadget>
<output>77</output>

<gadget id="calculator">110 - 77</gadget>
<output>33</output>

<result>33</result>