if alexandra increases her usual driving speed by 15 km/h, it will take her 2 hours less to make a trip to her gradnparents house. If she de

Question

if alexandra increases her usual driving speed by 15 km/h, it will take her 2 hours less to make a trip to her gradnparents house. If she decreaseshe rusualy speed by 15 km/h, it will take her 3 h more than usualy to make the trip. How long is the trip?

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Ximena 2 weeks 2021-09-11T00:11:30+00:00 1 Answer 0

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    2021-09-11T00:12:48+00:00

    Answer:

    Therefore,

    Distance of the trip is

    Distance =900\ km

    Step-by-step explanation:

    Let “x” be the Speed of the car and,

    “y” be the time to cover the trip to her grandparents,

    To Find:

    How long is the trip = ?

    Solution:

    We Know that,

    Distance = Speed\times Time

    According to the First given condition,

    Speed = x + 15

    Time = y - 2

    According to the Second given condition,

    Speed = x - 15

    Time = y + 3

    As we  know Distance will remain same so we have

    Distance = Speed\times Time= x\times y

    Substituting the values we get

    (x+15)\times (y-2)=(x-15)\times (y+3)=x\times y

    So on  Substituting we have

    (x+15)\times (y-2)=(x-15)\times (y+3)

    5x-30y=15\\Divding\ by\ 3\\x-6y=3…………..Equation ( 1)

    Again on  Substituting we have

    (x-15)\times (y+3)=x\times y

    3x-15y=45\\Dividing\ by\ 5\\x-5y=15………..Equation ( 2)

    Subtracting Equation 1 from equation 2 we get

    x- x -5y--6y=15-3\\\\y=12

    Substitute y = 12 in equation 1 we get

    x-6\times 12=3\\x = 72+3=75

    So we have now,

    Speed = 75\ km/h

    Time = 12\ h

    Therefore the Distance of the trip is

    Distance = x\times y=75\times 12=900\ km

    Therefore,

    Distance of the trip is

    Distance =900\ km

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45:7+7-4:2-5:5*4+35:2 =? ( )