There are 90 tons of goods in the warehouse, and 5 trucks are transported away, each truck has a ton, how many tons are left in the warehouse.
仓库有90吨货物，运走5车，每车a吨，仓库还剩多少吨．
<gadget id="calculator">90 - 5</gadget>
<output>85</output>

<result>85</result>