A car travels 50 kilometers per hour, and the gasoline it carries can be used for up to 6 hours. In the case of no refueling, in order to ensure the return to the starting point, how many kilometers should be driven back?
一辆汽车每小时行驶50千米，所带的汽油最多可以用6小时，在不加油的情况下，为保证返回出发地，最多开出多少千米就应往回行驶了？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<result>150</result>