What style of writing should you use in the following situations: Write F (formal), S (semi-formal), I (informal). 

1. a letter of complaint to the manager of a department store
2. an article for a teen magazine on the latest trends in clothes
3. a letter to your friend asking him for advice on which university to attend
4. a news report about an accident that happened in your town
5. a letter to a former teacher of yours, thanking him for his advice