Well, think of a fraction. The numerator is telling what how many you have and the denominator is the total amount available. A fraction can be written as a/b, or whatever how much value a you have out of the total amount you can have. So if you have 3 apples out of the available 3 apples, you have 100% of the apples. So the attritibutes are a/b when a and b are the same value, and when dividing fractions, when you divide by the reciprocal.
