if $|x-3|= \frac {\epsilon}{|x+3|} = \delta$
if we take a given value of $\epsilon$, then $x$ is constrained to some value by the above equation. Is there a function, lets say $g()$, that will give that $x$ value, given $\epsilon$ as the input, so that we can compute $\delta$ as $\frac {\epsilon}{g(\epsilon) + 3}$. Or, alternatively, is there some way that, knowing the above relation, we can find $\delta$ given $\epsilon$?