Two cars drive towards each other from two places at the same time. After 4.5 hours, the two cars meet at a distance of 9 kilometers from the midpoint. The express car travels 42 kilometers per hour. How many kilometers are there between places A and B?
两车从两地同时开出相向而行，4.5小时后两车在距中点9千米处相遇，快车每小时行42千米，甲乙两地相距多少千米？
<gadget id="calculator">4.5 * 42</gadget>
<output>189</output>

<gadget id="calculator">189 - 9</gadget>
<output>180</output>

<gadget id="calculator">180 * 2</gadget>
<output>360</output>

<result>360</result>