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Math·Advanced Math·Nonlinear equations in one variable and systems of equations in two variables

hard

$-5x(x+5)=15$

One solution to the given equation can be written as $\frac{-s+\sqrt{t}}{2}$, where $s$ and $t$ are positive integers. What is the value of $\frac{s}{t}$?

A

$\frac{5}{37}$

B

$\frac{5}{22}$

C

$\frac{5}{13}$

D

$\frac{10}{13}$