Lizzy: Eric has 20 marbles. He has 12 white marbles, 6 blue marbles, and the rest are green marbles. How many green marbles does Eric have?.
Me: Hmmm, let me think. I think this is the detailed solution:
Eric has a total of 12 + 6 = 18 white and blue marbles. Thus, he has 20 - 18 = 2 green marbles. Final answer: 2.