This document discusses a math problem involving sets. It asks to prove that A Δ B = (A - B) U (B - A), where A = {1, 2, 3, 4, 5} and B = {3, 4, 5, 6, 7}. It shows the step-by-step working, finding the elements of A Δ B, A - B, and B - A, and demonstrating they are equal, proving the original statement.