In[]:=
NExpectation[RR>1/(1/S+1/T)>P,{TUniformDistribution[{-1,1}],RUniformDistribution[{-1,1}],PUniformDistribution[{-1,1}],SUniformDistribution[{-1,1}]}]
NExpectation
:Invalid input.
Out[]=
0.0871246+0.189662