The average of the two numbers A and B is 50, and the number C is 80. What is the average of these three numbers?
甲乙两数平均数是50，丙数是80，这三个数的平均数是多少．
<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">100 + 80</gadget>
<output>180</output>

<gadget id="calculator">180 / 3</gadget>
<output>60</output>

<result>60</result>