interesting question:

answer is:
There are 0.1808 troy ounces of silver in 1 silver Washington quarter(s).

There are 0.0723 troy ounces of silver in 1 silver Roosevelt dime(s).

I will let you do the math from this point depending on how many of each coin you have. You also have to understand these numbers are for new issued coins. Not ones that have seen a lot of pocket wear and some of the silver is gone.

Dennis