Two cars drive towards each other at the same time from two places 405 kilometers apart. After 4.5 hours, the two cars meet. It is known that the passenger car travels 48 kilometers per hour. How many kilometers per hour does the truck travel? (solution by equation)
两车从相距405千米的两地同时开出相向而行，4.5小时后两车相遇，已知客车每小时行48千米，货车每小时行多少千米？(用方程解)
<gadget id="calculator">48 * 4.5</gadget>
<output>216</output>

<gadget id="calculator">405 - 216</gadget>
<output>189</output>

<gadget id="calculator">189 / 4.5</gadget>
<output>42</output>

<result>42</result>