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Math Help - A very simple question about addition/subtraction

  1. #1
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    A very simple question about addition/subtraction

    Hi as you will see my maths is rubbish but I am trying to learn and would be most grateful for some help.
    This is a basic algebra problem that I am trying to solve
    x+3-k=6-3k
    the answer is given as
    X=3-2k

    I got as far as
    X-k=3-3k
    so
    X-k+k=3-3k+k
    so to get X=3-2k
    3-3 must equal 3, this I don't understand, I would have thought 3-3=0?
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  2. #2
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    Re: A very simple question about addition/subtraction

    Quote Originally Posted by KDJA View Post
    Hi as you will see my maths is rubbish but I am trying to learn and would be most grateful for some help.
    This is a basic algebra problem that I am trying to solve
    x+3-k=6-3k
    the answer is given as
    X=3-2k

    I got as far as
    X-k=3-3k
    so
    X-k+k=3-3k+k
    so to get X=3-2k
    3-3 must equal 3, this I don't understand, I would have thought 3-3=0?
    On the left hand side you have 3 - 3 = 0, on the right hand side you have 6 - 3 = 3.
    Last edited by Prove It; July 23rd 2012 at 02:17 AM.
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  3. #3
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    Re: A very simple question about addition/subtraction

    Quote Originally Posted by KDJA View Post
    Hi as you will see my maths is rubbish but I am trying to learn and would be most grateful for some help.
    This is a basic algebra problem that I am trying to solve
    x+3-k=6-3k
    the answer is given as
    X=3-2k

    I got as far as
    X-k=3-3k
    so
    X-k+k=3-3k+k
    so to get X=3-2k
    3-3 must equal 3, this I don't understand, I would have thought 3-3=0?
    You seem to thinking of 3- 3k+ k as (3- 3)- (k+k) but that is not what is meant at all. "3k" means "3 times k" so you cannot combine that 3 with the other. Instead it is 3+(-3k+ k)= 3+ (-2k).
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  4. #4
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    Re: A very simple question about addition/subtraction

    This is how to solve this equation.

    x+3-k=6-3k

    x = 6-3-3k+k

    x = 3-2k

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