Can someone tell me if question 7 and 8 are right? can you also pleas explain quickly how?

Equation for the calculation double 2 and then add 5

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?

How can you construct perpendicular lines and prove theorems about perpendicular lines