Пошаговое объяснение:
2/17 * 14/15 + 2/49 * 14/15 - 1/7 * 14/15 + 3/49 * 14/15 =
= 14/15 * (2/17 + 2/49 - 1/7 + 3/49) =
= 14/15 * ( (2/17 - 1/7) + (2/49 + 3/49) ) =
= 14/15 * ( (14/119 - 17/119) + 5/49) =
= 14/15 * (-3/119 + 5/49) =
= 14/15 * (-21/833 + 85/833) =
= 14/15 * 64/833 = 128/1785