The child's home is 660 meters away from the school. The child walked 40 meters to school in the morning. How many meters away is he from the school?
小童家离学校660米，小童早晨上学走了40米，他离学校还有多少米？
<gadget id="calculator">660 - 40</gadget>
<output>620</output>

<result>620</result>