Help. ​

Extend UR through to some point P

Then....the measure of amgle PRS   = (1/2)minor arc RS   =  (1/2)(82)  = 42°

And by the exterior angle theorem, m< PRS  =  m< U + m< S....so......

42°  = m< U  + 30°     subtract 30° from each side

12°   =   m< U