math

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can you solve this equation by using simultaneous equations and can you write the method please?

Sarah and Louise have a combined age of 24. Six years ago Sarah was triple Louise's age. What is Sarah and Louise's ages now. Let Sarah be x and Louise be y.

thankyou

Harry

  • math -

    S + L = 24
    (S-6) = 3 (L-6)

    solve first for L
    L = (24 - S)

    Multiply second out
    S - 6 - 3 L - 18
    S = 3 L -12

    substitute our L from the first equation in the second equation
    S = 3 (24 - S) - 12
    S = 72 - 3 S -12
    4 S = 60
    S = 15
    then use the first equation to find L
    L = 24 - 15
    L = 9

    then check
    Now
    15 + 9 = 24 , yes they add to 24 check
    Six years ago
    15-6 = 9
    9 - 6 = 3
    sure enough, 9 is three times 3, check

  • math - Typo fix -

    S + L = 24
    (S-6) = 3 (L-6)

    solve first for L
    L = (24 - S)

    Multiply second out
    S - 6 = 3 L - 18
    S = 3 L -12

    substitute our L from the first equation in the second equation
    S = 3 (24 - S) - 12
    S = 72 - 3 S -12
    4 S = 60
    S = 15
    then use the first equation to find L
    L = 24 - 15
    L = 9

    then check
    Now
    15 + 9 = 24 , yes they add to 24 check
    Six years ago
    15-6 = 9
    9 - 6 = 3
    sure enough, 9 is three times 3, check

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