Extension Mystery Cache

This puzzle is a combination of a word puzzle, a number sequence puzzle, and basic arithmetic.

1. Rearrange the letters of the word "extension" to create the names of three whole numbers.
2. Write the three numbers in the three yellow boxes below in increasing order to create a number sequence.
3. Continue the sequence by finding the next nine numbers to put in the remaining boxes in increasing order.
4. Take the numbers that correspond to the letters in the sequence and use to solve for "X" in this equation: X=(K+L+M+N)-(A+B+C+D+E+F+G+H+I+J)+(J-D)
5. Take "X" and subtract from the last three numbers of the North fake coordinates and then subtract 402 to obtain the final North coordinates.
6. Take "X" and add to the last three numbers of the West fake coordinates and then add 300 to obtain the final West coordinates.

You can check your answers for this puzzle on GeoChecker.com.

Notes:

04/18/2017: geocache moved to a different location.