Four of the same trucks can transport 320 tons per day. According to this calculation, if 480 tons are to be transported per day, how many such trucks need to be added?
4辆同样的卡车，每天可运320吨，照这样计算，如果每天要运480吨，需要增加多少辆这样的卡车？
<gadget id="calculator">320 / 4</gadget>
<output>80</output>

<gadget id="calculator">480 / 80</gadget>
<output>6</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<result>2</result>