A bag contains black, white, and red marbles. The number of white marbles is 2 more than the number of black marbles, and the number of red marbles is 4 times the number of white marbles. Which of the following could be the total number of marbles in the bag?
Let the number of black marbles be B, then the number of white is B+2, and the number of red=4×white=4(B+2). Total number of marbles in the bag is algebraically B+B+2+4B+8=6B+10. I don’t have the figures to make a choice of answer, but if I take 10 away from each answer choice the result has to be divisible by 6. So I would reject any answer where 6 doesn’t divide into the total less 10.
