Dad, Mom took Xiaolin to the Great Wall to play. They go back and forth by coach. One-way fare: 12.4 yuan per person, half price for children under 1.4m. Kobayashi is 1.34m tall. His father bought round-trip tickets for three people and paid the conductor 100 yuan. How much should the conductor get back?
爸爸，妈妈带小林去长城玩．他们坐旅游汽车往返．单程票价：12.4元∕人，儿童票1.4m以下半价．小林身高1.34m，爸爸买了3个人的往返票，付给售票员100元．售票员应该找回多少钱？
<gadget id="calculator">12.4 * 2</gadget>
<output>24.8</output>

<gadget id="calculator">12.4 / 2</gadget>
<output>6.2</output>

<gadget id="calculator">24.8 + 6.2</gadget>
<output>31</output>

<gadget id="calculator">31 * 2</gadget>
<output>62</output>

<gadget id="calculator">100 - 62</gadget>
<output>38</output>

<result>38</result>