Please answer this correctly

Lin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 k= 3/12= 0.25 step 2 y= 0.25x where did joylin make her first error?

How to find the exponential function y=ca^x, with points (1,2) and (2,1)

What is the inverse of f(x) = 6x -24