I am having trouble trying to solve this equation when I use the thin lens equation it always wrong, it may be my signs. Here is the question:

A converging lens , F1 = 10cm is placed 30cm to the left of a diverging lens, f2 = -15cm . An object is placed 19cm to the left of the converging lens. Located the final image and its magnification.

I know the thins lens equation is 1/f = 1/di + 1/do and the magnification is di/do, but im not sure how to place my signs. THANKS!