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Dee W
Lv 7
Dee W asked in Science & MathematicsMathematics · 1 decade ago

28) A train travels 220 km for the start of a trip and 180 km for the last part. Total time 7hr. Rate per?

each part of the trip? The speed for the second part is 5 km faster than the first part.

My brain is tired and I can't remember this, any ideas out there?

1 Answer

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  • Pi R Squared
    Lv 7
    1 decade ago
    Favorite Answer

    Hi,

    220 . . 180

    ------ + ------ = 7

    x . . . .x+5

    Multiply every term by x(x + 5) to eliminate fractions. Then solve.

    220(x + 5) + 180x = 7x(x + 5)

    220x + 1100 + 180x = 7x² + 35x

    400x + 1100 = 7x² + 35x

    7x² - 365x - 1100 = 0

    (7x + 20)(x - 55) = 0

    x = 55 <= rate for the first 220 km <==ANSWER

    x + 5 = 60 <=rate for the last 180 km <==ANSWER

    I hope that helps!! :-)

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