The distance between the east and west cities is 405 kilometers. A freight train travels from Xicheng to Dongcheng at a speed of 55 kilometers per hour. Three hours later, a passenger train travels from Dongcheng to Xicheng at a speed of 65 kilometers per hour. How many hours does the bus meet the train after leaving?
东西两城相距405千米．一列货车以每小时55千米的速度从西城开往东城，开出3小时后，一列客车以每小时65千米的速度从东城开往西城．客车开出后几小时和火车相遇？
<gadget id="calculator">55 * 3</gadget>
<output>165</output>

<gadget id="calculator">405 - 165</gadget>
<output>240</output>

<gadget id="calculator">55 + 65</gadget>
<output>120</output>

<gadget id="calculator">240 / 120</gadget>
<output>2</output>

<result>2</result>