Mr. Chen drove from Louta to Hangzhou to participate in teacher training. He drove for 30 minutes on the ordinary road and the expressway around the city. It is known that the average speed of the ordinary road is 1200 m/min, and the average speed of the expressway is 1800 m/min, how many kilometers did he drive in total?
陈老师自驾车从楼塔出发去杭州参加教师培训，在普通公路和绕城高速公路上各行驶了30分钟，已知普通公路行驶的平均速度是1200米/分，高速公路行驶的平均速度是1800米/分，他总共行驶了多少千米？
<gadget id="calculator">1_200 * 30</gadget>
<output>36_000</output>

<gadget id="calculator">1_800 * 30</gadget>
<output>54_000</output>

<gadget id="calculator">36_000 + 54_000</gadget>
<output>90_000</output>

<gadget id="calculator">90_000 / 1_000</gadget>
<output>90</output>

<result>90</result>