This is a two-step cache. When you arrive at the posted coordinates, you should be at a gazebo. Look for a plaque. If you stand on your head, you might see a phone number on this plaque. Use the 4 digits of this number in the order they appear to solve for the coordinates of the cache.
N 39° F.G
W 86° H.I
where F = (A - B)(C + D - B)
G = A(D + C)(D + B) - A(B + D + C) - B
H = A + B
and I = D*C(C - B)^(D - B) + C - B
Final coordinates should keep you in the park, so check your work if not. Park is part of Carmel Clay Parks & Recreation, so hours are dawn to dusk.