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Math Help - How to re-arrange the formula to make 'n' the subject

  1. #1
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    How to re-arrange the formula to make 'n' the subject

    Hello

    How do I rearrange this formula to make 'N' the subject?

    ((1.86x1-1)xN)+((-1)x(100-N)) = 7.88

    I know that the parenthesis might not make complete sense, but this is a formula I am using in Microsoft Excel which works fine. At present I have values for 'N' which give me 7.88. There are other occasions where I have the value result, but do not know 'N'.

    It's a long time since I have had to rearrange something like this. There are 2 N's which confuses me. Thanks in advance.

    Dan Wright
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  2. #2
    Super Member Aryth's Avatar
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    For simplicity, I will exchange $ for

    ((1.86\$1 - \$1)N) + ((-\$1)(100 - N)) = \$7.88

    1.86(N)(\$1) - N(\$1) -100(\$1) + N(\$1) = \$7.88

    Now we group all terms with an N in them:

    (1.86(N)(\$1) - N(\$1) + N(\$1)) - 100(\$1) = \$7.88

    1.86(N)(\$1) - 100(\$1) = \$7.88

    N(1.86(\$1)) = \$7.88 + 100(\$1)

    N = \frac{\$7.88 + 100(\$1)}{1.86(\$1)}

    That's what I got, remember to switch the dollar sign for the euro sign. :P
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  3. #3
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    Thanks Aryth. That works great although I am finding it hard to understand how the the rearrangement rules work. I am also trying to re-arrange the formula to find 'T', but have not had any luck with that either.

    Anyone have any ideas?

    ((Tx1-1)x58)+((-1)x(100-58)) = 7.88

    Thanks in advance.

    Dan Wright
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