Not at the dummy coordinates. No pencil in the cache box.
You need to solve and find the coordinates for the following puzzle
cache: British
Pluck?. You will need the coords in order to find this one (see
below).
Here's an entirely new, but related, puzzle.
L-M, N-P, R-S
Then X=L*M*R + S - 1
Y - 1 = X/(P-N)
To find this cache, use X to adjust the Westing of GC19BZR. Use Y
to adjust the Northing of GC19BZR.
You can check your answers for this puzzle on
Geochecker.com.