There are three ribbons whose lengths are: 12cm, 16cm, and 23cm. What is their average length?
有三条丝带的长度分别是：12cm、16cm、23cm，它们的平均长度是多少．
<gadget id="calculator">12 + 16 + 23</gadget>
<output>51</output>

<gadget id="calculator">51 / 3</gadget>
<output>17</output>

<result>17</result>