A passenger car and a truck drive from city A to city B at the same time. It is known that the passenger car travels an average of 89 kilometers per hour, and the truck travels an average of 71 kilometers per hour. How many kilometers are the distance between the two cars after four hours?
一辆客车和一辆货车同时从甲城开往乙城．已知客车平均每小时行驶89千米，货车平均每小时行驶71千米，四小时后两车相距多少千米？
<gadget id="calculator">89 - 71</gadget>
<output>18</output>

<gadget id="calculator">18 * 4</gadget>
<output>72</output>

<result>72</result>