A linear function f(x) and its inverse f-1(x) intersect at the point (5,5). Create a function, f(x) that would satisfy this requirement

Answer 1

y = m x + b

inverse
x = m y + b
y = (x-b)/m
-----------------
5 = 5 m + b or 5 m = 5 - b
5 = (5-b)/m or 5 m = 5 - b
---------------------------
5 m = 5 - b
if m = 1
5 = 5 + b and b = 0
5 = (5-b)and b = 0
so
f(x) = x should do
(that should have been obvious :)