4) (x- 21/31 ) + 14/31 = 25/31
Х - 21/31 + 14/31 = 25/31 х = 25/31+21/31-14/31 х = 32/31 х = 1целая 1/31
( Х - 21/31 ) + 14/31 = 25/31 Х - 21/31 = 25/31 - 14/31 Х - 21/31 = 11/31 Х = 11/31 +21/31 Х = 32/31 или 1 1/31 проверяем: ( 32/31 - 21/31 ) + 14/31 = 25/31 всё верно