For a batch of steel, 45 small trucks are used to load it; if a large truck is used to load it, 36 vehicles are used, and each small truck loads 4 tons less than each large truck. How many tons is this batch of steel?
一批钢材，小卡车装载要用45辆；如果用大卡车装载，要用36辆，每辆小卡车比每辆大卡车少装4吨．这批钢材有多少吨？
<gadget id="calculator">45 - 36</gadget>
<output>9</output>

<gadget id="calculator">36 / 9</gadget>
<output>4</output>

<gadget id="calculator">4 * 4 * 45</gadget>
<output>720</output>

<result>720</result>