The distance between A and B is 900 kilometers. A passenger car and a truck drive from A to B at the same time. The bus arrives 5 hours earlier, and the truck travels 600 kilometers when the bus arrives at B. What is the speed of the bus in kilometers per hour?
甲乙两地相距900千米，一列客车和一辆货车同时由甲地开往乙地，客车早到5小时，客车到达乙地时货车行了600千米．问客车的速度是每小时多少千米？
<gadget id="calculator">900 - 600</gadget>
<output>300</output>

<gadget id="calculator">300 / 5</gadget>
<output>60</output>

<gadget id="calculator">900 / 60</gadget>
<output>15</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<gadget id="calculator">900 / 10</gadget>
<output>90</output>

<result>90</result>