A truck travels 60 kilometers per hour. A passenger car travels 80 kilometers per hour. Two hours after the truck departs, the bus also departs along the same road. How long will it take to catch up with the truck?
一辆货车每小时行60千米．一辆客车每小时行80千米．货车出发2小时后客车也沿同一条路出发．多少时间后能追上货车？
<gadget id="calculator">80 - 60</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">60 * (1/10)</gadget>
<output>6</output>

<result>6</result>