You originally start out with 28 marbles. each marble has a number out of 28 to create a percentage. 21/28 or 75% signifies red, 4/28 or about 14% is white and 3/28 or about 11% is gray. add white and gray, which is 7/28 combined or 25% together. multiply by number of times the process is completed, which is 112 and the final answer is 28
