Solve the following math problem efficiently and clearly:

- For simple problems (2 steps or fewer):
Provide a concise solution with minimal explanation.

- For complex problems (3 steps or more):
Use this step-by-step format:

## Step 1: [Concise description]
[Brief explanation and calculations]

## Step 2: [Concise description]
[Brief explanation and calculations]

...

Regardless of the approach, always conclude with:

Therefore, the final answer is: $oxed{answer}$. I hope it is correct.

Where [answer] is just the final number or expression that solves the problem.

Problem: Using the bar graph, what is the positive difference between the number of students at the school with the largest enrollment and the number of students at the school with the smallest enrollment?

[asy]
size(250);
defaultpen(fontsize(9));

fill((0,0)--(40,0)--(40,20)--(0,20)--cycle,lightgray);

draw((0,20)--(0,0)--(40,0));

draw((-0.5,2)--(40,2));
draw((-0.5,4)--(40,4));
draw((-0.5,6)--(40,6));
draw((-0.5,8)--(40,8));
draw((-0.5,10)--(40,10));
draw((-0.5,12)--(40,12));
draw((-0.5,14)--(40,14));
draw((-0.5,16)--(40,16));
draw((-0.5,18)--(40,18));
draw((-0.5,20)--(40,20));

filldraw((2.5,0)--(2.5,12.5)--(7.5,12.5)--(7.5,0)--cycle,lightblue);

draw((10,0)--(10,-0.5));
draw((20,0)--(20,-0.5));
draw((30,0)--(30,-0.5));
draw((40,0)--(40,-0.5));

filldraw((12.5,0)--(12.5,14.3)--(17.5,14.3)--(17.5,0)--cycle,lightblue);
filldraw((22.5,0)--(22.5,19)--(27.5,19)--(27.5,0)--cycle,lightblue);
filldraw((32.5,0)--(32.5,17.2)--(37.5,17.2)--(37.5,0)--cycle,lightblue);

label("0",(-0.5,0),W);
label("200",(-0.5,2),W);
label("400",(-0.5,4),W);
label("600",(-0.5,6),W);
label("800",(-0.5,8),W);
label("1000",(-0.5,10),W);
label("1200",(-0.5,12),W);
label("1400",(-0.5,14),W);
label("1600",(-0.5,16),W);
label("1800",(-0.5,18),W);
label("2000",(-0.5,20),W);

label("Varsity",(5,-2));
label("Northwest",(15,-2));
label("Central",(25,-2));
label("Greenbriar",(35,-2));

label("School",(20,-5), fontsize(11));
label(rotate(90)*"Number of Students",(-7,10), fontsize(11));
label("Total Enrollment",(20,24), fontsize(12));

label("1250",(5,12.5),S);
label("1430",(15,14.3),S);
label("1900",(25,19),S);
label("1720",(35,17.2),S);

[/asy]
user