Anonymous
Anonymous asked in Education & ReferenceHomework Help · 1 month ago

I need to solve by substitution ?

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  • David
    Lv 7
    1 month ago

    If: 3x - 5y = 4 and y = 4x - 28 

    Then: 3x - 5(4x - 28) = 4 => 136 = 17x => x = 8

    Solutions: x = 8 and y = 4

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  • 1 month ago

    y = 4x - 28

    3x - 5y = 4

    Substitute for y = 4x - 28

    3x - 5(4x - 28) = 4

    Distribute

    3x - 20x + 140 = 4

    Combine like terms

    -17x = -136

    Divide both sides by -17

    x = 8 <–––––

    plug in x = 8

    y = 4(8) - 278

    y = 32 - 28

    y = 4 <–––––

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