The distance between A and B is 280 kilometers. The two cars drive from opposite places respectively and meet each other after 3.5 hours. It is known that the passenger car travels 42 kilometers per hour, how many kilometers per hour does the truck travel? (Solution of column equation)
甲乙两地相距280千米，两车分别从两地相对开出，经过3.5小时相遇．已知客车每小时行42千米，货车每小时行多少千米？(列方程解)
<gadget id="calculator">42 * 3.5</gadget>
<output>147</output>

<gadget id="calculator">280 - 147</gadget>
<output>133</output>

<gadget id="calculator">133 / 3.5</gadget>
<output>38</output>

<result>38</result>