There are several ways such as
255
/ 7
First put it in the decimal equation
Since there is a decimal in the number being divided(255.5), you move the decimal so that it is a whole number(2555) but since you move the decimal place once, you do the same to the 7 so that it is now 70. So now it's 2555/70 which looks like 365 but then, you have to place the decimal value so that it is now 36.5
This is what you use to divide as shown.
Are you looking for the slop of the graph