The distance between A and B cities is 720 kilometers. A train of passenger cars and a train of trucks depart from the two cities at the same time. They meet after 4 hours. It is known that the speed of the trucks is 2/3 that of the passenger cars. What is the average speed of the trucks per hour? ?
甲乙两城相距720千米，一列客车和一列货车同时从这两个城市相对开出，4小时后相遇，已知货车的速度是客车的(2/3)，货车平均每小时行多少千米？
<gadget id="calculator">720 / 4</gadget>
<output>180</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 + (2/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">180 / (5/3)</gadget>
<output>108</output>

<gadget id="calculator">180 - 108</gadget>
<output>72</output>

<result>72</result>