Please help with this (Wasn't sure what subject, so its in math I guess)

What is the area of triangle abc if a = 8, b = 11, and c = 15?

Your food costs are $5,500. your total food sales are $11,000. what percent of your food sales do the food costs represent?

Two cars which are 40 miles apart start moving simultaneously in the same direction with constant speeds. if the speed of the car which is behind is 56 mph and the speed of the other car is 48 mph, how many hours will it take for the car which is behind to catch up the car ahead of it?