The magnification is also equal to image distance/object distance or v/u.

Magnifications don't always have to be bigger than one. For example in a camera and in your eyes the image is smaller than the object.

For a convex lens with an object distance of 15 cm and an image distance of 7.5 cm the magnification would be 7.5/15 or +0.5, the image is real and half the size of the object.