Marc\textquotesingle s watch is $15$ minutes slow while George\textquotesingle s watch is $7$ minutes fast. If the time on Marc\textquotesingle s watch is $11.50$ a.m. now, what time will George\textquotesingle s watch show in half an hour\textquotesingle s time? 
Overseas Competition->Knowledge Point->Combinatorics->Time Problem