A train of passenger trains and a train of freight trains leave two cities at the same time. The passenger train travels 40 kilometers per hour, and the speed of the freight train is 4/5 that of the passenger train. The two trains meet after 2.5 hours. How many kilometers are the distance between the two cities?
一列客车和一列货车同时从两个城市相对开出，客车每小时行40千米，货车的速度是客车的(4/5)，两车开出2.5小时后相遇，两城相距多少千米？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 * (4/5)</gadget>
<output>32</output>

<gadget id="calculator">40 + 32</gadget>
<output>72</output>

<gadget id="calculator">72 * 2.5</gadget>
<output>180</output>

<result>180</result>