д) 1/7 + 2/21 + 3/7 = (3/21) + (2/21) + (9/21) = 14/21 = 2/3
в) 7/10 + 2/15 + 11/30 = (21/30) + (4/30) + (11/30) = 36/30 = 6/5
е) 1/15 + 2/45 + 7/15 = (3/45) + (2/45) + (21/45) = 26/45
ж) 1/12 + 1/8 + 1/12 = (2/24) + (3/24) + (2/24) = 7/24
д) 1/7 + 2/21 + 3/7 = (3/21) + (2/21) + (9/21) = 14/21 = 2/3
в) 7/10 + 2/15 + 11/30 = (21/30) + (4/30) + (11/30) = 36/30 = 6/5
е) 1/15 + 2/45 + 7/15 = (3/45) + (2/45) + (21/45) = 26/45
ж) 1/12 + 1/8 + 1/12 = (2/24) + (3/24) + (2/24) = 7/24