In the car lot, 4/12 of the cars are white and 3/12 of the cars are blue. what fraction of the cars in the lot are either white or blue? i don't get it that much

Luigi is the first person to finish a 5k race and is standing 13 feet beyond the finish line. another runner, mario, is still running the race and has approximately 24 feet before he reaches the finish line. what is the distance between mario and luigi? explain through words, numbers or pictures how you found the answer.