The number of fifth-grade students going home by car after visiting the exhibition hall is three times that of those who take small cars. 6 people get off the car while driving. After that, the number of people on the big car is four times that of the small car. How many people are there on the big car?
五年级学生去展览馆参观后乘车回家，乘大汽车的人数是乘小汽车的人数的3倍．汽车行驶途中各有6人下车，之后，大汽车上的人数是小汽车上的人数的4倍，大汽车上原有多少人．
<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">12 * 1</gadget>
<output>12</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

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

<result>54</result>