In the ancient city of Jingzhou, there was a mysterious rectangular garden. The garden's perimeter was 120 steps, and its area was 500 square steps. Legend has it that the garden's owner hid the treasure in the city, and the latitude and longitude of the treasure are related to the garden's length and width. The owner left a riddle:
"Length plus eighteen, add sixteen, is the subtlety of latitude; width forty, minus three, is the subtlety of longitude. The benchmark is North Latitude 39, East Longitude 116."
Please calculate the precise location of the treasure based on the hints.
At first glance, it seems like a treasure hunt problem, but Rong Xianning immediately saw through it and realized it was a positioning problem. The calculated result was the location of his companion.
This involves a significant amount of equation operations and arithmetic, Rong Xianning murmured, "The subtlety of latitude, the subtlety of longitude..."
