Question

Decide if the function f is invertible.
f(w) is the cost of mailing a package weighing w pounds.

Answer 1

Does the cost of mailing a package go up if it is heavier? Does it only go up? Is it "strictly increasing"?

Answer 2

If f(w) = f(x) does that necessarily mean that w=x? If so, this function is invertible.

Answer 3

Thank you!