Two passenger and freight vehicles set off at the same time from cities A and B, which are 900 kilometers apart, and head toward each other. It is known that it takes 10 hours for a bus to go from city A to city B, and it takes 15 hours for a truck to go from city B to city A. How many hours did the two cars meet after departure?
客、货两车分别从相距900千米的甲乙两城同时出发，相向而行．已知客车从甲城到乙城需要10小时，货车从乙城到甲城需要15小时．两车出发后多少小时相遇．
<gadget id="calculator">900 / 10</gadget>
<output>90</output>

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

<gadget id="calculator">90 + 60</gadget>
<output>150</output>

<gadget id="calculator">900 / 150</gadget>
<output>6</output>

<result>6</result>