Hey, does anyone know the answer?

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

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?

2/3(-6y+9x) expand each expression using the distributive property