Answer:
-1005/1
Step-by-step explanation:
Consider School year starting to be x and the Average cost to be y.
So in terms of points you have (2003, 15505), (2004, 16510) and so on...
To find the slope you would use the formula m=y2-y1/x2-x1
15505-16510/2004-2003
-1005/1 <That's your slope