If I was Stagecoach Sunderland I would be running service

56 Sunderland - Newcastle (every 30 Mins) PVR 6
42 - Sunderland - Silksworth (every 30 Mins) PVR 3
60 - Sunderland - Parkside (every 30 Mins) PVR 5
20X - Sunderland - Durham (every 30 Mins) PVR 5
Extend the 3 to Low Moorsley too PVR 2 Extra