We want to perform the difference of two sets, we will get:
X - Y = {∅}
If we have two sets:
A = {a₁, a₂, ...}
B = {b₁, b₂, ...}
We define the difference as:
A - B = A - (A ∩ B)
This means that we just "remove" the common elements between A and B from A.
Here we have:
X = {9, 25}
Y = {1, 3, 9, 16, 25}
Then the common elements are:
9 and 25.
X ∩ Y = {9, 25}
Then we have that:
X - Y
Is equal to the set X with the elements {9, 25} removed. But notice that these are the two elements of X, then we end with an empty set, so we will have:
X - Y = {∅}
If you want to learn more, you can read:
https://brainly.com/question/3092724