Вычеслите 3/7+4/9 8.9-7.8 13/15-2/3 20/21+3/7 17/18-11.12 7.16 +1.6 2/9+5/6 10/21+9/14 7/9-4/15

3/7+4/9=27/53+28/53=55/53=1 2/53
8,9-7,8=1,1
13/15-2/3=13/15-10/15=3/15=1/5
20/21+3/7=20/21+9/21=29/21=1 8/21
17/18-11/12=34/36-33/36=2/36=1/18
7,16+1,6=8,96
2/9+5/6=4/18+15/18=19/18=1 1/18
10/21+9/14=140/294+189/294=329/294=47/42=1 5/42
7/9-4/15=105/135-36/135=69/135=23/45

3/7+4/9=27/63+28/63=55/63

8,9-7,8=1,1

13/15-2/3=13/15-10/15=3/15=1/5

20/21+3/7=20/21+9/21=29/21=1 8/21

17/18-11,12=17/18-11 12/100=17/18-11 3/25= 17/18-278/25=425/450-5004/450=- 4579/450=10 29/450

7,16+1,6=8,76

2/9+5/6=12/54+45/54=57/54=1 3/54=1 1/18

7/9-4/15=35/45-12/45=23/45

10/21+9/14=40/84+54/84=94/84=47/42=1 5/42