I need help i suck at math

The diameter of a circular chip is doubled to use in a new board game. the area of the new chip will be

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

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?