Does anyone know how the three squres are filled? I do not know what it means what I marked in blue

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?

Secant be and cf intersect at point d inside a what is the measure of cde

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83