The graph represents the gallons of water in a water tank with respect to the number of hours since it was completely filled.

the total capacity of the water tank , and the rate of change per hour.

Total capacity of the water tank is 400 gallons

Rate of change in water level is 20 gallons per hour

Step-by-step explanation:

The graph attached represents the gallons of water in a water tank with respect to the number of hours since it was completely filled.

The total capacity of the water tank is represented by the y-intercept of the graph that is 400 gallons.

Now to calculate the rate of change in water level we will take two points on the given line and find the slope.

There are two points (0, 400) and (5, 300) on the line.

So slope of the line =

                                =

This minus notation of slope shows that level of water is reducing and rate of change in water level is 20 gallons per hour.