The slope-intercept form of this line is y=15x-10, where 15 is the slope and -10 is the y-intercept.
To find slope, use m=(y2-y1)/(x2-x1), given points (x1,y1) and (x2,y2). Let’s use the first two points, (2,20) and (4,50). m = (50-20)/(4-2) = 30 / 2 = 15. The slope is 15.
To find the y-intercept AND the slope-intercept form use point-slope form y - y1 = m(x-x1). We’ll use the point (2,20) again. y - 20 = 15(x - 2), or y = 15x + 20 - 30, or y = 15x - 10. So, our y-intercept is -10 and our slope-intercept form of the line is y = 15x - 10.