Which step is the same in the construction of parallel lines and the construction of a perpendicular line through a point on the line?

-create only one arc that intersects the original line.
-create two arcs that intersect the original line.
-place the compass on a point off the original line.
-place the compass on a point on the original line.

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?