I'm trying to rearange this equation

for Mu s

That is the greek letter Mu subscript s... the static coeficent of friction

m2 = m1 sin theta - Mu s m1 cos theta

ok I got this

Mu s = -((m1 cos theta)^-1 (m2 - m1 sin theta))

ok I know that sin over cosine is tangent but I cant simplfy this any further correct?

by the way this is a problem were a block is sitting on a ramp at rest and is attached to another block hanging free by a string and i did a free body diagram and rearanged some stuff to determine a relationship among variables were I had enough information to solve the coeficent of static friction...

i just need to know if i can simplify that anymore

No, that is it. Most would write tan theta.