If there are 19 red marbles in every 1 black marble, and there’s a total of 120 marbles, that means 120/19, is equal to nearly 6.3 black marbles, but since you can’t split a marble in half, it would mean that there are 6 black marbles in total. Since, 19 * 6 is 114 & there’s a remainder of 6 to approach the final answer of 120, meaning there are 6 black marbles in the bag.
