Xiaohua bought 3 ribbons. The red ribbon is 14 cm long, the blue ribbon is 24 cm long, and the yellow ribbon is 16 cm long. What is their average length in cm?
小华买了3条丝带，红丝带长14厘米，蓝丝带长24厘米，黄丝带长16厘米，它们平均长度是多少厘米？
<gadget id="calculator">14 + 24 + 16</gadget>
<output>54</output>

<gadget id="calculator">54 / 3</gadget>
<output>18</output>

<result>18</result>