A truck travels 84 kilometers in the first two hours and 42 kilometers per hour in the next three hours. How many kilometers per hour does the truck travel on average?
一辆卡车前两小时行84千米，后3小时，每小时行42千米，这辆卡车平均每小时行多少千米？
<gadget id="calculator">42 * 3</gadget>
<output>126</output>

<gadget id="calculator">84 + 126</gadget>
<output>210</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">210 / 5</gadget>
<output>42</output>

<result>42</result>