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Math Help - Substitution

  1. #1
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    Substitution

    It's been awhile since i've done substitution and the notes i've taken seem to make no sense to me. I have a big unit test on Wednesday and am in need of help.

    How would I solve this equation in substitution?

    x + y = 27
    y = 3x +7

    I've tried to do this equation numerous times but am unable to do it.

    Any help please?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by largebabies View Post
    It's been awhile since i've done substitution and the notes i've taken seem to make no sense to me. I have a big unit test on Wednesday and am in need of help.

    How would I solve this equation in substitution?

    x + y = 27
    y = 3x +7

    I've tried to do this equation numerous times but am unable to do it.

    Any help please?
    plug the second equation into the first (substitute the expression for y), you get

    x + (3x + 7) = 27

    nw solve for x. when done, solve for y by plugging in your x-value in either equation
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