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    When a number X is increased by 10% its value becomes Y. When anumber Z is decreased by 10% its value becomes Y. By that percentagemust X be increased so its value equals Z?


    All i have is Y= 11X/10 and Y=9Z/10
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    (Original post by ErniePicks)
    When a number X is increased by 10% its value becomes Y. When anumber Z is decreased by 10% its value becomes Y. By that percentagemust X be increased so its value equals Z?


    All i have is Y= 11X/10 and Y=9Z/10
    You have two simultaneous equations there.. what can you do?
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    (Original post by SeanFM)
    You have two simultaneous equations there.. what can you do?
    If i substitute it in then it's 11X/10=9Z/10 i have no diea what to do next.
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    (Original post by ErniePicks)
    If i substitute it in then it's 11X/10=9Z/10 i have no diea what to do next.
    Good job :borat:

    So if you look at going from X to Y, a 10% increase means you do 11/10 * X = Y (which you've done already), so the number you're going from * the percentage it's increasing/decreasing by = the new number.

    So if you wanted to make your substituted equation look like the X to Y one, what would you do?
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    (Original post by SeanFM)
    Good job :borat:

    So if you look at going from X to Y, a 10% increase means you do 11/10 * X = Y (which you've done already), so the number you're going from * the percentage it's increasing/decreasing by = the new number.

    So if you wanted to make your substituted equation look like the X to Y one, what would you do?
    I'm really sorry but i don't really understand it. Is the equation

    (11/10*X)* N%=(9/10X)

    That doesn't look right to me, but even if it i have no clue where to go from there
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    (Original post by ErniePicks)
    I'm really sorry but i don't really understand it. Is the equation

    (11/10*X)* N%=(9/10X)

    That doesn't look right to me, but even if it i have no clue where to go from there
    Not quite.

    For X and Z you have a single fraction (which represents the percantage) multiplied by X or Z to get 1 * Y (or just Y).

    So you want there to be a single fraction that you multiply X by to get Z and from that fraction you can work out the answer.
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    (Original post by SeanFM)
    Not quite.

    For X and Z you have a single fraction (which represents the percantage) multiplied by X or Z to get 1 * Y (or just Y).

    So you want there to be a single fraction that you multiply X by to get Z and from that fraction you can work out the answer.
    I am so sorry i just can't seem to wrap my head around this. Is there a worked example of a similar question to this explaining the steps that you have a link for or the name of what type of question this is so i could search around?

    Once again so sorry, i really appreciated your help
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    (Original post by ErniePicks)
    I am so sorry i just can't seem to wrap my head around this. Is there a worked example of a similar question to this explaining the steps that you have a link for or the name of what type of question this is so i could search around?

    Once again so sorry, i really appreciated your help
    Not to worry. I think if you understand how to do this question you'll be fine if you ever see it again.

    If I asked you to make Z the subject of the formula (the substituted one) what would you do? And how does that answer look similar to the two equations that you started with?
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    (Original post by SeanFM)
    Not to worry. I think if you understand how to do this question you'll be fine if you ever see it again.

    If I asked you to make Z the subject of the formula (the substituted one) what would you do? And how does that answer look similar to the two equations that you started with?
    I would just divide both sides by 9/10 and that means it would be Z= 11/10*10/9*X
    which is 110/90*X which is equivalent to 1.22*z= x OHHHHHH SO THATS HOW X HAS TO INCREASE BY 22% TO EQUAL Z!!!!!!! jesus sosrry i have no idea how i didn't manage to put that together. Thank you so much for the help, i think if i ahd put it in as ratios (0.9 and 1.1) i would have noticed sooner. Thanks so much mAN
 
 
 
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