The answer is 2(8x² - 13x + 10)
Since the expression is the sum of 2 angles of total 5 angles in the pentagon, the measure of two angles is:
(40x² - 65x + 50) * 2/5 =
= (5 * 8x² - 5 * 13x + 5 * 10) * 2/5 =
= 5(8x² - 13x + 10) * 2/5 =
= (8x² - 13x + 10) * 2 =
= 2(8x² - 13x + 10)