Xiaohua's house and Xiaoqing's house are both in the west of the school. Xiaohua's house is 500 meters away from the school, and Xiaoqing's house is 800 meters away from the school. How many meters are there between them?
小华家和小青家同在学校的西面，小华家离学校500米，小青家离学校800米，他们两家相距多少米．
<gadget id="calculator">800 - 500</gadget>
<output>300</output>

<result>300</result>