The distance between A and B is 678 kilometers. A bus travels from city A to city B at a speed of 52 kilometers per hour. After 3 hours, a truck travels from city B to city A at a speed of 64 kilometers per hour. How many hours after the truck leaves, does it meet the passenger car?
甲、乙两地相距678千米，一辆客车从甲城开往乙城，每小时行52千米，3小时后，一辆货车从乙城开往甲城，每小时64千米．货车开出几小时后和客车相遇？
<gadget id="calculator">52 * 3</gadget>
<output>156</output>

<gadget id="calculator">678 - 156</gadget>
<output>522</output>

<gadget id="calculator">52 + 64</gadget>
<output>116</output>

<gadget id="calculator">522 / 116</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>