а) 4/5 + 3/7 = 1 8/35
4/5 = 28/35, 3/7 = 15/35; 28/35 + 15/35 = 43/35 = 1 8/35 - несократима
б) 5/12 + 4/45 = 91/180
12| 3 2 2 - 15; 45| 5 3 3 -4; 5/12 = 75/180; 4/45 = 16/180; 75/180 + 16/180 = 91/180 - несократима; 91| 13 7; 180| 5 3 3 2 2
в) 5/18 + 4/45 = 11/30
5/18 - 25/90; 4/45 = 8/90; 25/90 + 8/90 = 33/90 = 11/30 - несократима
г) 8/33+ 2/11 = 14/33
2/11 = 6/33; 8/33 + 6/33 = 14/33 - несократима
д) 12/17 + 27/34 = 1 1/2 (0,5)
12/17 = 24/34; 24/34 + 27/34 = 51/34 = 1 17/34 = 1 1/2 = 1,5
е) 8/21 + 7/18 = 97/126
8/21 = 48/126 - 6; 7/18 = 49/126 - 7; 48/126 + 49/126 = 97/126; 97 - простое число, несократима