65. One glass contains water, the other contains the same amount of milk. A spoonful of milk is taken from the second glass, poured into the first glass, and mixed. Then a spoonful of the mixture is taken from the first glass and poured into the second glass. Which is greater: the amount of milk in the water or the amount of water in the milk?
65. Let there be $a$ spoons of liquid in each glass. Pouring a spoon of milk into the glass of water, we get $a+1$ spoons of the mixture, in which milk constitutes $\frac{1}{a+1}$ part. Taking a spoon of the mixture, in which water constitutes $\frac{a}{a+1}$ part, and pouring it into the glass of milk. In it, there will be a total of $a$ spoons of liquid, and water will constitute $\frac{a}{a+1}: a=\frac{1}{a+1}$ part. Therefore, the water in the milk will be $\frac{1}{a+1}$ part and the milk in the water will also be $\frac{1}{a+1}$ part.