When multiplying a number by 10, move the decimal to the right. When multiplying a number by 0.1, move the decimal to the left. Why? :( HELP IM TiMED

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.