To add these fractions, we need to find a common denominator. The common denominator for 6, 9, 12, and 19 is 18.

So, the expression becomes:

-5/18 + 6/18 - 5/18 + 15/18

Now, we can add the fractions:

-5/18 + 6/18 - 5/18 + 15/18 = 1/18

Therefore, the final answer is 1/18.