1) -4+(-7) = -4-7 = -11
2) -0,46+(-0,89) = -0,46-0,89 = -1,35
3) -2,3+(-0,86) = -2,3-0,86 = -3,16
4) -5 7/9+(-3 4/9) = -5 7/9-3 4/9 = -8 11/9 = -9 2/9
5) -5/8+(-11/12) = -5/8-11/12 = -15/24-22/24 = -37/24 = -1 13/24
6) -4 5/14+(-7 9/21) = -4 5/14-7 9/21 = -4 5/14-7 3/7 = -4 5/14-7 6/14 = -11 11/14