Can anyone answer these questions properly?

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?

Mr. piper is driving peter, roddy, and scott home from school. all of them want to ride in the front seat. how can he make a fair decision about who rides in the front seat?

The perimeter of the rectangle is 120 feet. if the length of the rectangle is ten feet more than the width ,what are the dimensions (length and width) of the rectangle?