There are 18.5 liters of gasoline in the mailbox of Uncle Li’s car, and each liter of gasoline can drive 6.4 kilometers.
李叔叔汽车邮箱里有18.5升汽油，每升汽油可行驶6.4千米，李叔叔到外地办事往返路程200千米，至少忘邮箱里加入多少升汽油？
<gadget id="calculator">200 / 6.4</gadget>
<output>31.25</output>

<gadget id="calculator">31.25 - 18.5</gadget>
<output>12.75</output>

<result>12.75</result>