It takes 45 tons of cement to be transported by truck, and 15 tons have already been transported. The rest will be transported by a truck with a load of 5 tons at one time. How many such trucks are needed?
用货车运水泥，要运45吨，已经运了15吨，剩下的用载重5吨的货车一次运完，需要几辆这样的货车？
<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<result>6</result>