A passenger car and a truck leave opposite each other from places A and B which are 609 kilometers apart at the same time. After 7 hours, the two cars meet and the bus travels 42 kilometers per hour. How many kilometers per hour does the truck travel? (solution with equation)
客车和货车同时从相距609千米的甲乙两地相对开出，经过7小时两车相遇，客车每小时行42千米，货车每小时行多少千米？(用方程解答)
<gadget id="calculator">609 / 7</gadget>
<output>87</output>

<gadget id="calculator">87 - 42</gadget>
<output>45</output>

<result>45</result>