The posted coordinates will bring you to the entrance to the Olson Cemetery where Michael B. Olson and Julia B. Olson buried their four children: Michael, Amelia, Julia and Milten.
In order to find this cache you must locate the markers for the Olson family then determine their ages at death.
The final can be found at: N41 26.ABC W88 41.XYZ
Where:
A = Amelia Olson
B = Milten Olsen divided by 3
C = Michael Olson
X = Julia B. Olson minus Michael B. Olson
Y = Julia Olson divided by 2
Z = Michael Olson