This has nothing to do with my "Ask Your Kids" series other than a similar title. However, most people these days will have to ask their parents if they want to understand the joke. Hint: it has nothing to do with firearms.
Well... That is... Um... Oh dear...never mind that. Please just go talk to your parents.
The puzzle is a standard cryptarithm following the standard conventions of the puzzle: Each letter stands for exactly one digit. Each digit is represented by exactly one letter. (That is, there is a one-to-one correspondence between the letters and digits.) Please don't try to make up awkward conditions, because there aren't any.
The two equations are sums. They are taken together. That is the letters in the first stand for the same digits in the second. You will need to solve both sums simultaneously. The solution is unique.
The cache is at N 37: 33.DDX. W 122: 16.XAS.
The cache is a magnetic hide-a-key in sorta the usual place. You'll figure it out when you get there. My original coordinates put me in the middle of the parking lot so I used Google Earth to refine them. FTF prize is a Sacagewea Dollar.