'' the length of one side of an equilateral is 3x+2. its perimeter is 60 centimeters. write an equation that could be used to find the value of x. solve for x and then find the length of the side. '' HELP

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?