Pointing in the right direction.
Please do not use my variable names.
You should get a rough idea from this.

int TotalSeconds = SecondsS + SecondsB + SecondsR;
  int CarriedMinutes = TotalSeconds / 60;
  int ResultSeconds = TotalSeconds % 60;

  int TotalMinutes = MinutesS + MinutesB + MinutesR + CarriedMinutes;