Average rate of change is another name for slope
(big hint given in the units feet per second).
Slope is change in y / change in x — the slope formula is (y2 – y1)/(x2 – x1)

Use the two points (3, 6.26) and (9, 3.41) for (x1, y1) and (x2,y2).
Show your work.  Because 3.41 is less than 6.26, your answer should be negative.