A passenger car and a truck drive from city A to city B at the same time. The bus travels 81 kilometers per hour, and the truck travels 72 kilometers per hour. After 6 hours, the bus arrives at city B, and it takes several hours for the truck to reach city B. ?
一辆客车和一辆货车同时从甲城开往乙城，客车每小时行81千米，货车每小时行72千米，6小时后，客车达到乙城，再经过几小时货车才能到达乙城？
<gadget id="calculator">6 / 72</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">81 * (1/12)</gadget>
<output>27/4 = around 6.75</output>

<gadget id="calculator">(27/4) - 6</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>