(5b - 3)² - (5b - 2)(5b + 2) = (5b)² - 2 * 5b * 3 + 3² - ((5b)² - 2²) =
= 25b² - 30b + 9 - 25b² + 4 = - 30b + 13
(5b - 3)² - (5b - 2)(5b + 2) = (5b)² - 2 * 5b * 3 + 3² - ((5b)² - 2²) =
= 25b² - 30b + 9 - 25b² + 4 = - 30b + 13