Answer:
STN = 65 Completing the 180 degrees
115+m(STN)=180
m(STN)=65
mNTR=115
because The NTR and MTS meet theyself
mRTM=65
same The NTR and MTS
because RTM ans STN meet theyself
hopefully you understand it
i am trying hard to explain the question when i solve it but my engilish is not helping to handle it