Slope Intercept form is y=mx+b where m is the slope and b is the y-intercept. The line crosses through (0,3) so b=3.
To find the slope, count the units between two points and form a ratio of vertical to horizontal distance. Count from (0,3) to (1,0). It drops -3 units and moves to the right 1 unit. So m = -3/1 = -3.
