Olivia filled an empty horse trough with water. the water level, in centimeters, is proportional to time elapsed, in minutes, since she began filling the trough. the graph above shows this relationship.

For this case, the first thing you should know is that the point (8,28) is an ordered pair or equivalently a point P (x, y).
 This point represents the following rate:
 28/8 = 3.5 cm / min.
 Equivalently, it means that Olivia filled after 8 minutes, 28 centimeters of water. He did it at a speed of 3.5 cm / min.
 answer
 Time = 8 minutes
 Water level = 28 centimeters
 Speed = 3.5 cm / min