As salam mualaikum. My place of residence is in City A which is about 65 km from City B. I travel to City B on Fridays, and the day after (Saturday morning) I travel from City B to City C (City C is 90+ km from City B) to do some part-time work. I have two questions:
 When I come back from work in City C (Saturday afternoon) do I pray Qasr salat in City B for the rest of the day?;
 Instead of praying Dhur in City C (while working), can I combine Dhur (after the time for dhur has passed (asr has began)) in City B?
On Monday mornings, I travel back to City A (my place of residence) and do the same the Friday afterwards. I would be grateful if someone could reduce my confusion on this matter.