For example, if I have:
$$t\left (\frac{2\mu}{3}-\mu r \right )=r-\mu$$
I find very easily what is $t(r,\mu)$:
$$t(r,\mu)=\frac{r-\mu}{ \left (\frac{2\mu}{3}-\mu r \right ) }$$
Now, I need to find the whole expression what is $t(r,\mu)$ in this case below: $$t\left (\frac{2\mu}{3}-\mu r \right )+t^2 \left (\frac{\mu}{4}-\frac{\mu r}{3} \right )+t^3 \left (\frac{\mu}{15}-\frac{\mu r}{12} \right )=r-\mu$$
Any help about this would mean a lot for me.
Just a follow up to the comment by @Delta-u...Using Mathematica one gets the following solutions to the cubic equation: