I need the ratio of x to y in this equation:

sum [n*(x/10)^n/10^(n-2)] == y from n=1 to ∞


Thank you!

## closed as off-topic by Johu, Jens, Daniel Lichtblau, m_goldberg, Henrik SchumacherSep 20 '18 at 5:29

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• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – Johu, Jens, Daniel Lichtblau, Henrik Schumacher
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• Is this about Mathamatica the software, or is it about math? Should we then forward the question to Mathematics? – Johu Sep 19 '18 at 23:23

Solve[Sum[n (x/10)^n/10^(n-2),{n,1,\[Infinity]}]==y/.x->a y,a]/.a->x/y

x/Sum[n (x/10)^n/10^(n - 2), {n, \[Infinity]}]

(-100 + x)^2/10000