问一道英语奥数题Lily wants to walk from A to B,there are two roads i
问一道英语奥数题
Lily wants to walk from A to B,there are two roads in front of her.If a is 10km,b is 6 miles.She walked from A to B on road a at a speed of 20m every minute,and come back on road b.How long did she spend together?
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