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Thread: Algebra problem->Check if right,pls

  1. #1
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    Question Algebra problem->Check if right,pls

    I'm having a hard time learning how to translate a written math problem into algebra equations. Tell me if this is right?

    The difference of two number, x and y, is 28. The number y is 8/9 of the number x. Find these 2 numbers.

    $\displaystyle x-y = 28$
    $\displaystyle 8/9 x = y$

    $\displaystyle -8(x-y) = -8(28)$
    $\displaystyle -8x-8y=-224$

    $\displaystyle 8/9x=y$
    $\displaystyle 9(8/9x)=9(y)$
    $\displaystyle 8x=9y$
    $\displaystyle 8x-9y=0$

    $\displaystyle -8x-8y=-224$
    $\displaystyle +8x-9y=0$
    $\displaystyle -17y=-224$
    $\displaystyle y=224/17$

    $\displaystyle x-y=28$
    $\displaystyle x-224/17=28$
    $\displaystyle x=28+224/17$
    $\displaystyle x= 700/17$

    $\displaystyle x-y=28$
    $\displaystyle 700/17-224/17=28$
    $\displaystyle 28=28$

    So what do you guys think?
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  2. #2
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    This part is wrong.

    Quote Originally Posted by Neenoon View Post

    $\displaystyle -8(x-y) = -8(28)$
    $\displaystyle -8x-8y=-224$
    it should be $\displaystyle -8x + 8y=-224 $

    You got the 2 equations right you solve the system wrong. The way you solve the problem is a bit complicated.
    Here is how I would do it.


    $\displaystyle x-y=28 $
    $\displaystyle y= \frac {8} {9} x $

    so

    $\displaystyle x-\frac {8} {9} x=28 $
    $\displaystyle \frac {1} {9} x=28 $
    $\displaystyle x= 252 $

    Plug x into the equation
    $\displaystyle 252-y=28$
    $\displaystyle y=224 $
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  3. #3
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    Duh

    Let's say I was tired when I did these!

    Thanks a whole bunch, 5 points that would have been gone right there!
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  4. #4
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    Quote Originally Posted by Neenoon View Post
    I'm having a hard time learning how to translate a written math problem into algebra equations. Tell me if this is right?

    The difference of two number, x and y, is 28. The number y is 8/9 of the number x. Find these 2 numbers.

    $\displaystyle x-y = 28$
    $\displaystyle 8/9 x = y$

    $\displaystyle -8(x-y) = -8(28)$
    $\displaystyle -8x-8y=-224$

    $\displaystyle 8/9x=y$
    $\displaystyle 9(8/9x)=9(y)$
    $\displaystyle 8x=9y$
    $\displaystyle 8x-9y=0$

    $\displaystyle -8x-8y=-224$
    $\displaystyle +8x-9y=0$
    $\displaystyle -17y=-224$
    $\displaystyle y=224/17$

    $\displaystyle x-y=28$
    $\displaystyle x-224/17=28$
    $\displaystyle x=28+224/17$
    $\displaystyle x= 700/17$

    $\displaystyle x-y=28$
    $\displaystyle 700/17-224/17=28$
    $\displaystyle 28=28$

    So what do you guys think?
    Hi!
    u can get this answer through solve the equation method also
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