Buying back an item at a lower price

Q: I am in the business of buying and selling car mags. A few months back, I sold a set of rims to someone for R1800. A couple of months later, I got a call from the same person asking if I want to buy these same rims back because he had no use for them. I made him an offer of R1200 and purchased them back. Is this considered as riba or is it permissible?

Choosing a spouse

Q: There is a girl I really like so I told my parents about her and finally my parents met her family. Now the situation was to take the final call. I asked my parents about their opinion and they said that since they met the girl and her family just once they might not know much about her and they asked me to take a decision. They also said that they are neither opposing her nor forcing me to marry her but they mentioned one point saying that I might get a better girl considering the fact that the girl and her family has little less knowledge and teachings of Islam and they also said that they wouldn't have preferred the girl. But again they said that they are OK with the girl if I select to go with her. So I am really confused right now. I dont want to hurt my parents and I dont know if they get hurt if I decided to go with this girl. Please help me.

Incorrect vow

Q: A person vowed that if he never changes his school, he will stop smoking. He has not changed his school till now but he has smoked many times in this time. Does he have to offer expiation and how many?