(357+289)-157 = 646 - 157 = 489
(863+471)-371 = 1334 - 371 = 963
643-(243+398) = 643 - 641 = 2
876-(398+476) = 876 - 874 = 2
(357+289)-157 = 646 - 157 = 489
(863+471)-371 = 1334 - 371 = 963
643-(243+398) = 643 - 641 = 2
876-(398+476) = 876 - 874 = 2