denise is 6 years older than her sister. 8 years ago she was 4 times as old as her sister how old is each girl now

Question

denise is 6 years older than her sister. 8 years ago she was 4 times as old as her sister how old is each girl now

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Eirian 3 years 2021-07-20T10:24:16+00:00 1 Answers 33 views 0

Answers ( )

  1. mocmien2
    0
    2021-07-20T10:25:38+00:00
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    Answer:

    Denise = 16

    Sister = 10

    Step-by-step explanation:

    D=denise

    S=sister

    Eq 1)   D=S+6

    Eq 2)  D-8 =4S-8

    replace D with S+6 in Eq 2

    (S+6)-8 = 4S -8

    S-2 = 4S -8

    add 8 to both sides

    S+6 =4S

    subtract S from both sides

    6 = 3S

    divide both sides by 3

    2 = S   ( this is the sister age 8 years ago )

    2+8 = 10  current age

    plug that into Eq 1)

    D = 10 +6

    D=16    (Denise’s current age)

    so

    Denise = 16

    Sister = 10

    if you subtract 8 from each , then there ages 8 years ago would be

    Denise =8

    Sister = 2

    and 2*4 = 8  

    this checks

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )