According to the given graph, we have a line with a positive slope, which means it's increasing, that is, the number of water increases while the number of minutes also increases.
To find the rate of increase, we have to use the following formula
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
Let's use the points (0,320) and (4, 640).
[tex]m=\frac{640-320}{4-0}=\frac{320}{4}=80[/tex]
The rate is 80 liters per minute.
At last, the amount of water in the tank at 0 minutes is 320 liters because that's the initial condition.
