I'm not sure how to do these
1.) mr. robins earns a commission on each airfare he books. at the end of the day, he had booked $208.60 worth of airfare and earned $31.29. what is the mr robins' commission rate?

2.) the bill at a restaurant came to $136.40. the patrons decided to leave a 15% rip. what was the total of the bill including tip?

3.) winter coats are marked 70% oof on february 1st. if a coat costs $57.75 on january 31st, how much will it cost on february 1st?