Respuesta :

mathmate
Take any of the valid pairs of points, use the formula
rate of change = (y2-y1)/(x2-x1)

Say we use P1=(0,21.4), P2=(3,19)
x1=0, y1=21.4
x2=3, y2=19

Rate of change = (21.4-19)/(0-3)=2.4/(-3) = -0.8 sq. ft/in of liquid