Lizzy: In 6 months Bella and Bob will be celebrating their 4th anniversary. How many months ago did they celebrate their 2nd anniversary?.
Me: Hmmm, let me think. I think this is the detailed solution:
First, we find their current point in time be realizing that 4 years is 4 sets of 12 months, meaning at that anniversary they will have been together 4 * 12 = 48 months. Then, we subtract their 6 month difference, finding they are at 48 - 6 = 42 months into their relationship. Since 2 years would be 2 * 12 = 24 months into the relationship. We take the larger number, 42, and subtract the smaller number, 24 to find the difference in months, meaning it is 42 - 24 = 18 months. Final answer: 18.