A bus carries a total of 42 passengers, some of whom get off the bus halfway, each ticket price is 6 yuan, and the other part get off at the terminal, each ticket price is 9 yuan, the conductor collects a total fare of 318 yuan, halfway How many people are in the car?
一辆公共汽车共载客42人，其中一部分人在中途下车，每张票价6元，另一部分人到终点下车，每张票价9元，售票员共收票款318元，中途下车的有多少人．
<gadget id="calculator">42 * 9</gadget>
<output>378</output>

<gadget id="calculator">378 - 318</gadget>
<output>60</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<result>20</result>