I know some of you are working hard on the Brain Teaser and may have a question or two. I will give a hint.
Help yourself by drawing a timeline and marking down Bill and Bob on the time line. Now remember this basic fact… if Bill was 10 years older than Bob years ago, he continues to be 10 years older today. I am using 10 as an example, this is not the actual age differential.
So, today Bill is twice as old as Bob was at an earlier point in time. At that earlier point in time, Bill was the same age that Bob is now. Draw this out on a timeline and it will help.