We know that A function has inverse if it is one-one and onto.
F={(a, 3),(b, 2),(c, 1)}
Since each element has unique image,
F is one-one.
Since for every image, there is a corresponding element, F is onto.
Since, function is both one-one and onto it will have inverse.
F = {(a, 3),(b, 2), (c, 1)}
F−1=(3,a),(2,b),(1,c)