Need help with the answer

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?

2. explain in words how you plot the point (4, −2) in a rectangular coordinate system.

Graph the equationy=x^2 -[tex]y = x^{2} - 2[/tex]