0.9397=0.85x -In x
x=((10000*ln(x)+9397)/8500)
\(x=\frac{10000 \times ln(x)+9397}{8500}\)
You'll need to use a numerical method, Newton-Raphson would work well.
(NB. the equation has two roots located at approximately 0.721 and 1.79).
Could also do it as follows:
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+426 
