Question 155
For a set of real numbers $A$, let $A-A$ be the set of distinct pairwise differences of $A$; that is,
$$
A-A := \{ a-b : a, b \in A \}
$$
If $|A-A| = 25$, find the sum of all possible values of $|A|$.
$$
A-A := \{ a-b : a, b \in A \}
$$
If $|A-A| = 25$, find the sum of all possible values of $|A|$.