Welcome to the end of the spice and herb series! YIPEEEEE
I hope you enjoyed the challenge of finding 26 caches!
I also hope you also read the actual descriptions regarding the spices and herbs (and one seasoning!).
When you found each of the 26 caches, you should have also found a number in the lid of each container. Hopefully you wrote those down as you will need that information to calculate the coordinates for the final cache's location.
Here is the math you will need to complete to get to the final. Use the information you found in the specific spice (i.e. the O spice number was 0).
N47 0 [(E-M)] . [(C*R) - (N+F)] [(Y - (A+O)] [(J-L) + (D+U)]
W123 0 [(B+H)] . [(G-P) + (X-T)] [(V+Z) - (S-K)] [(W*Q) - I)]
(Thank you to Mrs Seahawks12man for coming up with this equation!)
I will add a spoiler photo to ensure if you get close to the cache, you will find it!