If you are calculating the slope of two points on a grid. You would have an x,y coordinates. You would have point 1 and point 2. If your first point is 1,1 and your second point is 4,4 . you take (1-4)/1-4) which is -3/-3 which is equal to 1. I only call it real world because it would be used in computation. Many times in computers you use variables so you don't necessarily know which of the two numbers is greater so... rather than checking you just do the math and it all works out.
