Answer:
72000 miles
Step-by-step explanation:
If the distance between the students is 600 miles, and this implies in a 3 degree difference in the sun position, that means this 600 miles is related to 3 degrees of the circunference of the planet.
So, to find the whole circunference of the planet, that is, 360 degrees, we just need to use a rule of three:
3 degrees -> 600 miles
360 degrees -> x miles
3x = 600 * 360
x = 600 * 360 / 3 = 72000 miles