1) - 3/7+2/21=

2) 5/6 + (5/7) =

3) - 17/21+9/14=

4) 3,9 + (-3,9) +

5) 2,77 + (-1/4) =

6) 1/3 + (-1/2) =

7) 2 5/12 + (-17 3/8) =

8) - 29+17 1/8=

9) 17 + (-1,25) =

10) - 2 3/5 + (-7 3/10) =

11) 4 3/4 + (-4 11/12) =

4 3 (пробел значит 4 целых)

3/4 обыкновенная дробь

1) - 3/7+2/21=-9/21+2/21=-7/21

2) 5/6 + (-5/7) = 5/6-5/7=35/42-30/42=5/42

3) - 17/21+9/14=-34/42+27/42=-7/42=-1/6

4) 3,9 + (-3,9) = 3,9-3,9=0

5) 2,77 + (-1/4) = 2,77-0,25=-2,52

6) 1/3 + (-1/2) = 1/3-1/2=2/6-3/6=-1/6

7) 2 5/12 + (-17 3/8) = 2 5/12-17 3/8=2 10/24-17 9/24=2 10/24-16 33/24=-14 23/24

8) - 29+17 1/8=-28 8/8+17 1/8=-11 7/8

9) 17 + (-1,25) = 17-1,25=15,75

10) - 2 3/5 + (-7 3/10) = - 2 3/5-7 3/10=-2 6/10-7 3/10=-9 9/10

11) 4 3/4 + (-4 11/12) = 4 3/4-4 11/12=4 9/12-4 11/12=-2/12=-1/6