What the answer to 7+8=

Jessica is a custodian at oracle arena.she waxes 20 m2 of the floor in 3/5 of an hour. jessica waxes the floor at a constant rate.at this rate how many sqaures meters can she wax per hour

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?

If you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left