I'm studying for a precalc test and I've kind of hit a brick wall with conversion. I've searched for help but only found things on converting from pi radians.
I found some questions that consist of things like converting 7.58 rad to degree.
How do I do this, what is this type of conversion even called?
Whenever converting from one quantity to another, always remember to multiply by $1$.
We know that $2\pi\mathrm{~rad}=360^\circ$. This can be also be written as $\frac{2\pi\mathrm{~rad}}{360^\circ}=1$ or as $1=\frac{360^\circ}{2\pi\mathrm{~rad}}$.
If you want to convert, say, $7.58$ rad to degrees, just multiply by the $1$ that has rad in the denominator so that it cancels out and you get the units that you want (degrees).
$$\require{cancel}7.58\cancel{\mathrm{~rad}}\times\frac{360^\circ}{2\pi\cancel{\mathrm{~rad}}}\approx 434.3^\circ$$
If you want to convert, say, $200^\circ$ to radians, just multiply by the $1$ that has degrees in the denominator so that it cancels out and you get the units that you want (radians).
$$200\cancel{^\circ}\times\frac{2\pi\mathrm{~rad}}{360\cancel{^\circ}}\approx 3.49\mathrm{~rad}$$