Xiao Ming has to walk a total of 1,500 meters from school to home. He has already walked 780 meters from home. How many meters will he have to walk to reach school?
小明从学校到家一共要走1500米，他从家出发已经走了780米，他还要走多少米才能到达学校？
<gadget id="calculator">1_500 - 780</gadget>
<output>720</output>

<result>720</result>