Kylie explained that (-4x+9)^2 will result in a difference of squares because (-4x+9)^2= (-4x)^2+ (9)^2= 16x^2 +81. Which statement best describes kylie’s explanation

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?