Answer: because that is what the slope would look like
Step-by-step explanation:
when you graph this, you have a point at 2, 4 and 0, 8. when you go to 0, 8 and count down four so you now have to move to the right to get to 2, 4. You then move to the right 2 spaces. so, you moved (-4, 2) since this can be simplified, you then have (-2, 1) which is equal to -2. If this still doesnt make sense, go to Desmos.com and put (2,4) click the plus button then add expression then type (0,8). Count down -4 and over 2. Hope this helps