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Math Help - Algebra problem, dvds

  1. #1
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    Algebra problem, dvds

    Phil has three times as many DVDS as sam has. Even after Phil gives Sam 6 DVDs, he still has 16 more DVDs than Sam has. What was the original number of DVDs that Phil had?
    I set this up like so,
    P=3*S
    P-6=16+S+6

    (S=Sam)
    How do I solve this? Any answers appreciated!
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  2. #2
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    Re: Algebra problem, dvds

    Quote Originally Posted by Sewilliams13 View Post
    Phil has three times as many DVDS as sam has. Even after Phil gives Sam 6 DVDs, he still has 16 more DVDs than Sam has. What was the original number of DVDs that Phil had?
    I set this up like so,
    P=3*S
    P-6=16+S+6

    (S=Sam)
    How do I solve this? Any answers appreciated!
    Looks good. Now, since P= 3S, you can replace P in the second equation 3S: 3S- 6= 16+ S+ 6= S+ (16+ 6)= S+ 22.
    If you add 6 to both sides, that gives you 3S- 6+ 6= S+ 22+ 6 or 3S= S+ 28. Can you finish that?
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  3. #3
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    Re: Algebra problem, dvds

    Quote Originally Posted by HallsofIvy View Post
    Looks good. Now, since P= 3S, you can replace P in the second equation 3S: 3S- 6= 16+ S+ 6= S+ (16+ 6)= S+ 22.
    If you add 6 to both sides, that gives you 3S- 6+ 6= S+ 22+ 6 or 3S= S+ 28. Can you finish that?
    I can finish that, to end up getting 14=s. Thank you very much! What a simple blunder-_- All that frustration for nothing! My SAT book gave this strategy, which threw me off.
    P=3S P/3=S
    P-6=16+P/3+6
    P-6=48+P+18/3
    3P-18=48+P+18
    2P=84
    P=42.


    ^^The book (Grubers 2013) Is trying to say that this is a simpler strategy. I disagree. Thanks for the wonderful help!
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  4. #4
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    Re: Algebra problem, dvds

    Quote Originally Posted by Sewilliams13 View Post
    I can finish that, to end up getting 14=s. Thank you very much! What a simple blunder-_- All that frustration for nothing! My SAT book gave this strategy, which threw me off.
    P=3S P/3=S
    P-6=16+P/3+6
    P-6=48+P+18/3
    3P-18=48+P+18
    2P=84
    P=42.
    ^^The book (Grubers 2013) Is trying to say that this is a simpler strategy. I disagree. Thanks for the wonderful help!
    Well, it is simpler....since you're asked how many DVD's Phil has (not S); solution leads directly to Phil;
    doing it the other way leads to DVD's Sam has; you then need to substitute to get Phil.

    Btw, this: P-6=48+P+18/3
    requires brackets: P-6=(48+P+18)/3
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  5. #5
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    Re: Algebra problem, dvds

    Ahh that makes so much more sense with brackets!(they were not in the book ?) Thank you!!
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