The lines are perpendicular. find the slope-intercept form of the equation of line y₂

When you want to find the slope of the perpendicular line, all you have to do is flip the known slope upside down and make it negative. You know that slope is 3 and you know is perpendicular. So, just flip 3 upside down into  and then make it negative, -. If you look at the coordinate grid, you can see that crosses the y-axis at 4. When you put those into slope-intercept form you get = -x + 4.