An object is placed in front of a converging lens in such a position that the lens $(f=12.0 \mathrm{cm})$ creates a real image located $21.0 \mathrm{cm}$ from the lens. Then, with the object remaining in place, the lens is replaced with another converging lens $(f=16.0 \mathrm{cm}) .$ A new, real image is formed. What is the image distance of this new image?