I solved a number of these puzzles when they came out, and then some more a few months later. They started forming an embarrassingly large pile so we went off to collect them. I remember that it was a family trip as my (usually non-caching) wife came along too.
This was one that I hadn't solved at the time. I'm not sure why as I had understood what all the hints were pointing me towards. But I just couldn't see how to get any numbers from the pairs. Then just over a year ago I had another go and finally realised what "d" and "e" meant. From there it was just a matter of doing the maths and out popped the answer.
Bobcat is now on his Christmas holiday so I decided to take a day off too to do some caching with him. This was our first of the day.
We could see this was going to be a muggly area so we decided that I would pretend to make a phone call while Bobcat searched. However my pantomime skills were sadly unused: I stopped to start my performance but found that Bobcat had extracted the cache without even breaking step.
We were surprised to see that nobody has visited this since 10th December last year - so this was also an unintentional resurrection.
A nice puzzle - all very logical - so a fave point for this one.