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  • 我想問一道英文的數學題!

    我想問一道英文的數學題!
    John leaves home and start walking at 4 km/h to his friend's house.Half a hour later,his sister Susan leaves the house on a bicycle and heads in the same direction at 12 km/h.How far away are they from the house when Susan catches up to John,and how long after John fist left the house?
    英語人氣:487 ℃時間:2020-03-25 18:21:45
    優(yōu)質解答
    Susan追 John時,John已走了:4*0.5=2km
    Susan追上John需要時間:2/(12-4)=0.25h
    此時John離家距離:4*(0.5+0.25)=3km
    John離開家時間為:0.5+0.25=0.75h=45分鐘
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