There are 15 trucks in the parking lot, the number of buses is three times that of trucks, and the number of cars driving away is the same as that of buses. How many cars are there?
停车场有15辆卡车，大客车的辆数是卡车的3倍，小汽车开走5辆就与大客车同样多．小汽车有多少辆？
<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">45 + 5</gadget>
<output>50</output>

<result>50</result>