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Math Help - Unknown variables question

  1. #1
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    Unhappy Unknown variables question

    I have a math query relating to a calculation I'm required to do on a property auction website. Apologies if this is the incorrect forum but my understanding of different types of math is quite lacking!

    I have the following equation:

    w = 200,000
    x = 5% of 200,000
    y = 17.5% of x
    z = x + y

    w + z = a

    I now need to reverse this equation.

    m = w + z. m is known, w and z are unknown.

    Both variables to the right of the = are unknown but the percentages are constant, even so, surely this is impossible?

    Thanks in advance,


    cassiuscoal
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  2. #2
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by cassiuscoal View Post
    I have a math query relating to a calculation I'm required to do on a property auction website. Apologies if this is the incorrect forum but my understanding of different types of math is quite lacking!

    I have the following equation:

    w = 200,000
    x = 5% of 200,000
    y = 17.5% of x
    z = x + y

    w + z = a

    I now need to reverse this equation.

    m = w + z. m is known, w and z are unknown.

    Both variables to the right of the = are unknown but the percentages are constant, even so, surely this is impossible?

    Thanks in advance,


    cassiuscoal
    w = 200,000

    x = 5% of 200,000 = 10,000

    y = 17.5% of x = 17.5% of 10,000 = 1,750

    z = x + y = 10,000+1,750= 11,750

    w + z = a

    so, a = w+z= 200,000+11,750 = 211,750

    According to what you have written,

    w + z = a

    m = w + z

    So m = a = 211,750
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  3. #3
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    Sorry, thanks for your attempt harish but I think my original post confused things. Starting from scratch, ignoring the values in my first post; ill try and simplify it:

    z + y + x = 200,000

    y = 5% of z
    x = 17.5% of y
    z = ?

    What are x y and z based on 200,000?

    Cheers,

    cassiuscoal
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  4. #4
    Super Member Quacky's Avatar
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    Windsor, South-East England
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    I would recommend writing the percentages as decimals.

     <br />
y=5\%\times z=0.05z <br />

    x=17.5\%\times y <br />
= 0.175(0.05z) = 0.00875z

    Can you tidy up and finish? Just substitute those values into the equation in question.
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  5. #5
    Member rtblue's Avatar
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    Starting off from where Quacky left us, we have that

    x=0.00875z

    y=0.05z

    z=1z

    Now we continue, and add these up:

    0.00875z + 0.05z + z

    1.05875z=200,000

    z=188.9

    Since Y= 5% of Z, we have:

    188.9(0.05)=9.445= y

    So 9.445 is Y. Since X= 17.5% of y, we have:

    9.445(0.175)=1.652875= x

    So:

    x=1.652875

    y=9.445

    z=188.9
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  6. #6
    Super Member Quacky's Avatar
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    I had been hoping to let him/her finish for themself to check that he/she at least partially understands...nevermind
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