solution:
Think about f : {1, 2, 3} → {a, b, c} given by f(1) = a, f(2) = b and f(3) = c
So f = {(a, 1), (b, 2), (c, 3)}
Subsequently f-1 (a) = 1, f-1 (b) = 2 and f-1 (c) = 3 Now, f-1 = {(a, 1), (b, 2), (c, 3)}
Subsequently, backwards of f-1 = (f-1 )- 1 = {(1, a), ( 2, b), ( 3, c)} = f Hence (f–1)– 1 = f.