If f (x) = (x-a + a) / (x-a), the symmetry center of the image of its inverse function is (m, 3), then a =?

If f (x) = (x-a + a) / (x-a), the symmetry center of the image of its inverse function is (m, 3), then a =?

The symmetry center of the original function image is (3, m)
So a = 3, M = 1