There is no puzzle to do, just go to the posted coordinates and start following the directions. This is a 3-stage Multi.
Note that all locations are within the park so you do not need to exit the park for any of the stages, including the final.
Welcome to beautiful Windmill Island Gardens! Windmill Island is an actual island cut off from the mainland by a canal. If you haven't seen the famous De Zwaan windmill (an actual Dutch windmill) up close, this is your chance. The windmill's name is Dutch for The Swan or Graceful Bird. It is the oldest authentic, working Dutch windmill in the United States.
If you don't want to pay to enter the park, you can still enter when the park is closed. This is usually after 6 PM on days that it is normally open, except during Tulip Time.
At the posted coordinates you will see a sign with two words. Use the words as follows.
A = the # of letters in the first word
B = the # of letters in the second word.
Stage 2 is at N42 47.CDE W86 5.XYZ.
C = A + B - 2
D = (B * 2) / 4
E = Y - D
X = A
Y = A - B
Z = Y - E
Checksum 12, 12
At Stage 2 there will be some noticeable numbers. One is two digits and one is four digits.
The first number is MN and the second numbers is OPQR.
The Final is at N42 47.ABC W86 5.XYZ.
A = O
B = P + 1
C = N + 1
X = Q
Y = O - M
Z = R + 1
Checksum 17, 16
Now you know where to go. Please return it as you found it.