How do I do this problem?

danny-rogandanny-rogan
in Science & Mathematics

A motorboat goes 36km downstream in the same amount of time that it takes to go 24 km upstream. If the current is flowing at 3 km/h, what is the rate of the boat in still water?

Thanks

Comments

  • guyguy

    Let r = rate of the boat in still water

    24/(r - 3) = 36/(r + 3)

    Cross multiply:

    36(r - 3) = 24(r + 3)

    36r - 108 = 24r + 72

    36r - 24r = 72 + 108

    12r = 180

    r = 180/12 = 15 km/h

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