Calculate the average rate of change for the graphed sequence from n = 2 to n = 4

Calculate the average rate of change for the graphed sequence from n = 2 to n = 4.
graphed sequence showing point 1, negative 3, point 2, negative 3.5, point 3, negative 6.75, point 4, negative 10.125, point 5, negative 15.1875, and point 6, negative 22.78125