А) 19/45 3/5= 24/40, 1/8 = 5/40, 24/45 - 5/45 = 19 / 45
б) 1/12 1/3 = 4/12, 5/12 - 4/12 = 1/12
в) 7/20 1/5 = 4/20, 4/20 + 3/20 = 7/20
г) 13/21 3/7 = 9/21, 9/21 + 4/21 = 13/21
д) 19/30 4/5 = 24/30, 1/6 = 5/30, 24/30 - 5/30 = 19/30
е) 7/24 5/8 = 15/24, 1/3 = 8/15, 15/24 - 8/24 = 7/24