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math

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4x-y=7
5x+y=20

  • math -

    4 x - y = 7 Add y to both sides

    4 x - y + y = 7 + y

    4 x = y + 7 Subtract 7 to both sides

    4 x - 7 = y + 7 - 7

    4 x - 7 = y

    y = 4 x - 7


    5 x + y = 20

    5 x + 4 x - 7 = 20

    9 x - 7 = 20 Add 7 to both sides

    9 x - 7 + 7 = 20 + 7

    9 x = 27 Divide both sides by 9

    9 x / 9 = 27 / 9

    x = 3


    y = 4 x - 7

    y = 4 * 3 - 7

    y = 12 - 7

    y = 5

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