The distance between Xiaogang's home and school is 200 meters. He walked 50 meters to school, and then went home to get it without bringing a water bottle. How many meters did he walk from home to school today?
小刚从家到学校的距离是200米，他上学时走了50米，想到了没带水壶又回家去取，今天他从家到学校一共走了多少米．
<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">100 + 200</gadget>
<output>300</output>

<result>300</result>