Answer: The answer is one-tenth part.
Step-by-step explanation: Given that Greg is pouring an entire gallon of milk into 10 glasses. We are to find the part of the gallon in each glass.
We will be using unitary method here as follows.
In 10 glasses, the quantity of the milk contained is = 1 gallon.
Therefore, in 1 glass, the quantity of the milk contained is given by
Thus, one-tenth part of a gallon will be in each glass.