For the function f(x) = 5x1/5find f^-1(x)

Just tell me how to set up the equation.

The function f(x) = 14,600(1.1)* represents the population of a town x years after it was established. what was the original population of the town?

6. sarah saved $12.75 every week for a number of weeks, w. she received an additional $25 during the last week in which she saved money. write and solve an equation to find the number of weeks, w, for which sarah had saved money if she has $114.25 now.