What are the rate of changes for

39 & 16.5 =

30 & 12.4 =

28 & 10.4 =

19 & 10.3 =

23 & 11.2 =

39 & 16.5 = - 22.5

30 & 12.4 = - 17.6

28 & 10.4 = - 17.6

19 & 10.3 = - 8.7

23 & 11.2 = - 11.8

if the values are y values you will subtract them from each other to get the numerical value and because they all go from a larger number to a smaller number the rate is a negative. if they were from a smaller value to a larger value teh rates of change would be positive.