Answer:
19xyz
Explanation:
First, let us just forget about the xyz at the end of each number. Now, we just have the simple addition problem 3 + 7 + 9. First. let us do 3 + 7, which gives us 10. Now, let us take our 10 and add the 9 to it. 10 + 9 is 19. Now, we can add our xyz back to the equation. Now, we have 19xyz. As we do not know anything about what x, y, or z equals, nothing further can be done with this equation. Therefore, the answer is 19xyz.
Hope this helps! :D