Sorry about the other person that commented for points- I'll try to explain best I can, please let me know if you have any questions as I am not great at explaining.
1- 14 because I assume "After he left the school" means this does not include the 6 miles to the library so to get back home he would have to travel another six miles west and 8 miles south. 8+6= 14 if you did include the other 6 then that would =20 but that isn't an option so...
2- not sure? sorry hun but what i'm getting isn't an option
3- 40 minutes- 60 minutes/ 12 miles= 5 minutes per mile- 8miles*5minutes= 40 minutes
4- not sure? sorry hun but what i'm getting isn't an option