(6a - 7)² - (4a - 2)² = ((6a - 7) - (4a - 2))((6a - 7) + (4a - 2)) = (6a - 7 - 4a + 2)(6a - 7 + 4a - 2) = (2a - 5)(10a - 9) = (2a - 5)(10a - 9)