After completing Friedrich's Day Adventure Lab you have the opportunity to obtain a smiley through this bonus cache.
You will need to complete the Adventure Lab cache noting the locations in the order that Friedrich visited during his day.
Mobile app smart link to open the Adventure Lab
https://labs.geocaching.com/goto/FD
Using this equation you can calculate the coordinates to the final bonus location.
S 35 02.0AB E 138 48.CDE
A = location 1 minus 2
B = location 2 plus 4
C = location 3 minus 5
D = location 4 minus 5
E = location 5 minus 3
Check sum by adding all numbers together S = 22 E = 30