13*19-19*10+10*21-21*7+7*23-23*4+4*25-25

13 * 19 - 19 * 10 + 10 * 21 - 21 * 7 + 7 * 23 - 23 * 4 + 4 * 25 - 25 = (13 * 19 - 19 * 10) + (10 * 21 - 21 * 7) + (7 * 23 - 23 * 4) + (4 * 25 - 25) = 19 * (13 - 10) + 21 * (10 - 7) + 23 * (7 - 4) + 25 * (4 - 1 ) = 19 * 3 + 21 * 3 + 23 * 3 + 25 * 3 = 3 * (19 + 21 + 23 + 25) = 3 * (40 + 48) = 3 * 88 = 3 * 80 + 3 * 8 = 240 + 24 = 264;В итоге получили, 13 * 19 - 19 * 10 + 10 * 21 - 21 * 7 + 7 * 23 - 23 * 4 + 4 * 25 - 25 = 264.Ответ: 264.