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Math Help - "Simple" pre-algebra help please

  1. #1
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    "Simple" pre-algebra help please

    My son is in 4th grade, gifted/talented class.

    He's working on math "sentences" and specifically figuring out where to put parenthesis to make the sentence true. I know how to do this, and have helped with all the problems except for this one, and I just can't figure it out.

    I've tried several trains of thought, but simply can't figure out where the parenthesis should go to make the following mathematical statement true.

    Am I missing something?

    6 - 5 x 5 / 7 + 5 = -22 4/7
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  2. #2
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    Quote Originally Posted by feverpa View Post
    My son is in 4th grade, gifted/talented class.

    He's working on math "sentences" and specifically figuring out where to put parenthesis to make the sentence true. I know how to do this, and have helped with all the problems except for this one, and I just can't figure it out.

    I've tried several trains of thought, but simply can't figure out where the parenthesis should go to make the following mathematical statement true.

    Am I missing something?

    6 - 5 x 5 / 7 + 5 = -22 4/7
    6-(5x([5/7]+5))
    =6-(5x(40/7))
    =6-(200/7)
    =-158/7
    =-22 4/7
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  3. #3
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    Thank you so much for the explanation.

    One further question - is there a clue that tells you where to start?

    I thought the clue was 4/7, so I had to do the 5x5 (or -5x5) first, and divide that by 7 to get something that ended in 4/7

    did you get it by trial and error, or did you have a strategy based on something that I'm not seeing?

    thanks again.
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  4. #4
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    -22\ and\ \frac{4}{7}\ is\ -\frac{22(7)}{7}-\frac{4}{7}=-\frac{154+4}{7}=-\frac{158}{7}

    Using 7 as denominator, your equation is \frac{42}{7}-5  \frac{5}{7}+\frac{35}{7}

    You can begin to see that the brackets need to be around the last 2 fractions
    to get a number as high as -158 for the numerator.
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