Вычислите: 3/7+4/9, 8/9-78, 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, 9/14-3/7+15/28, 1/6+1/4-1/8, 13/18-29/45+8/15

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

8/9-78=8/9-702/9=-694/9=-77 цел 1/9

13/15-2/3=3/15-10/15=-7/15

20/21+3/7=20/21+9/21=29/21=1 цел 8/21

17/18-11/12=34/36-33/36=1/36

7/16+1/6=21/48+8/48=29/48

2/9+5/6==4/18+15/18=19/18=1цел 1/18

10/21+9/14=20/42+27/42=47/42=1цел 5/42

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

9/14-3/7+15/28=9/14-6/14+15/28=3/14+15/28=6/28+15/28=21/28=3/4=0,75

1/6+1/4-1/8=2/12+3/12-1/8=5/12-1/8=10/24-3/24=7/24

13/18-29/45+8/15=65/90-58/90+8/15=7/90+8/15=7/90+48/90=55/90=11/18