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Anonymous
Anonymous asked in 科學及數學數學 · 6 years ago

Math!Quick!20 point!Desmond...

Desmond and Jay have $800 in total.If Desmond gives $160 to Joy, Jay will have 1.5 times as much as Desmond has. How much does Desmond have?

Please help me!!!!!!!!!!!Thx@-@

1 Answer

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  • CK
    Lv 7
    6 years ago
    Favorite Answer

    I suppose this is "If Desmond gives $160 to [ Jay ]".

    Let D be the amount Desmond has and J be the amount of Jay.

    D + J = 800

    D = 800 - J

    If Desmond gives $160 to Jay, Jay will have 1.5 times as much as Desmond has

    (J+160)/(D-160) = 1.5 = 3/2

    2(J+160) = 3(D - 160)

    2J + 320 = 3[(800 - J) - 160]

    2J + 320 = 3(800 - J) - 3(160)

    2J + 320 = 2400 - 3J - 480

    2J + 320 = 1920 - 3J

    2J + 3J = 1920 - 320

    5J = 1600

    J = 1600/5 = 320

    D = 800 - J = 480

    Checking :

    (J+160)/(D-160) = (320+160)/(480-160) = 480/320 = 1.5

    2014-01-27 00:38:03 補充:

    If the question is "If Desmond gives $160 to Joy". then

    D + J = 800

    D = 800 - J

    If Desmond gives $160 to Joy, Jay will have 1.5 times as much as Desmond has

    J/(D-160) = 3/2

    2J = 3(D-160) = 3D - 480 = 3(800-J) - 480 = 2400 - 3J - 480 = 1920 - 3J

    2014-01-27 00:40:25 補充:

    2J = 1920 - 3J

    5J = 1920

    J = 1920/5 = 384

    D = 800 - J = 800 - 384 = 416

    D+J = 416+384 = 800

    J/(D-160) = 384/(416-160) = 384/256 = 1.5

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