Xiaoli has 3 colored ribbons, the first one is 14cm, the second one is 16cm, and the length of the third ribbon is so long that the average length of the three ribbons is 18cm.
小丽有3根彩带，第一根14厘米，第二根16厘米，第三根彩带长多少厘米可以使三根彩带的平均长度为18厘米．
<gadget id="calculator">18 * 3</gadget>
<output>54</output>

<gadget id="calculator">54 - 14 - 16</gadget>
<output>24</output>

<result>24</result>