The distance between A and B is 540 kilometers. A truck and a passenger car drive from the two places at the same time. After 4 hours, the two cars meet. The speed ratio of the truck and the bus is 7:8. How many kilometers per hour does the bus travel on average?
甲、乙两地相距540千米，一辆货车与一辆客车同时从两地相对开出，4小时后两车相遇，货车与客车的速度比是7：8．客车平均每小时行多少千米？
<gadget id="calculator">540 / 4</gadget>
<output>135</output>

<gadget id="calculator">7 + 8</gadget>
<output>15</output>

<gadget id="calculator">8 / 15</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">135 * (8/15)</gadget>
<output>72</output>

<result>72</result>