standard_description: Calculate the distance between numbers in the complex plane as the modulus of the difference, and the midpoint of a segment as the average of the numbers at its endpoints.
problem_activity: The function,
$$f$$
, defines the cost of supplies for a lemonade stand as a function of the number of cups of lemonade you expect to sell.
$$f(x) = .5x + 10$$
Write
$$f^{-1}$$
algebraically and define the domain and range for both
$$f$$
and
$$f^{-1}$$
in the context of the problem.


aligns: no