Thailand's important days Mystery Cache

There are a plenty of important days in Thailand such as Songkran festival, Chakkri memorial day some of them are holidays some of them are not but I prefer holidays because I can do geocaching =). 
In solving this puzzle you have to search the date of the given important days in this following 
1. King Rama IX's Coronation day = Z May 
Z-1 = A

2. Chulalongkorn day = XY October
X+Y = B

3. Constitution day = YZ December
(Y+Z)-1 = C

4. Chakri memorial day = X April
X+1 = D

5. Teacher's day = YZ January
Y+Z+1 = E

6. Mother's day = XZ August
X+Z = F

7. Father's day = Z December
Z-5 = G

8. National labour day = Y May
Y+4 = H

9. Songkran festival = XY to 1Z April
Z-Y-X-1 = I

10. King Taksin memorial day = XY December 
(Y/X)-3 = J

The final coordinates are
N 13   AB.CDE
E 100 FG.HIJ
Goodluck! (patkij helps me in hiding this cache)
*contact me if you have any trouble in solving or finding.