№579
б) 1 - 3/4 = 1/4 (1= 4/4 ; 4/4 - 3/4 = 1/4)
№580
б) 12 1/4 - 9 = 3 1/4 ( 12-9=3 + 1/4)
г) 10 8/9 - 2/9 = 10 2/3 ( 8/9 - 2/9 = 6/9 сокращаем на 3 = 2/3)
е) 7 4/9 - 1 1/9 = 6 3/9 (7-1=6; 4/9-1/9=3/9 сокращаем на 3 = 1/3)
№581
б) 6 - 3 2/5 = 2 3/5 (6-3=3; 3=2+5/5; 3- 2/5 = 2 3/5)
г) 8 - 3 3/4 = 4 1/4 (8-3=5; 5=4+4/4; 5-3/4= 4 1/4)
е) 7 - 1 2/3 = 5 1/3 (7-1=6; 6= 5+3/3; 6- 2/3 = 5 1/3)
надеюсь доступно)