1) 0,8 + 3/7 = 8/10 + 3/7 = 4/5 + 3/7 = 28/35 + 15/35 = 43/35 = 1 8/35
2) 3 1/3 - 2,5 = 3 1/3 - 2 5/10 = 3 1/3 - 2 1/2 = 3 2/6 - 2 3/6 = 2 8/6 - 2 3/6 = 5/6
3) 4,9 + 1 1/9 = 4 9/10 + 1 1/9 = 4 81/90 + 1 10/90 = 5 91/90 = 6 1/90
4) 26 1/11 - 5,7 = 26 1/11 - 5 7/10 = 26 10/110 - 5 77/110 = 25 120/110 - 5 77/110 = 20 43/110
5) 40,8 + 15 2/3 = 40 8/10 + 15 2/3 = 40 4/5 + 15 2/3 = 40 12/15 + 15 10/15 = 55 22/15
6) 18 5/13 - 9,5 = 18 5/13 - 9 5/10 = 18 5/13 - 9 1/2 = 18 10/26 - 9 13/26 = 17 36/26 - 9 13/26 = 8 23/26