The distance between the two cities is 450 kilometers. A passenger car and a truck leave the two cities at the same time. The truck travels 45 kilometers per hour, which is the speed of the passenger car (9/11). After the two cars leave, they meet after a few hours. ?
两个城市相距450千米，一列客车和一列货车同时分别从两城相对开出，货车每小时行45千米，是客车速度的(9/11)，两车开出后，经过几小时相遇？
<gadget id="calculator">9 / 11</gadget>
<output>9/11 = around 0.818182</output>

<gadget id="calculator">45 / (9/11)</gadget>
<output>55</output>

<gadget id="calculator">45 + 55</gadget>
<output>100</output>

<gadget id="calculator">450 / 100</gadget>
<output>9/2 = around 4.5</output>

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