1) -3/8 + (-3/8) = -6/8 = -3/4;
2) -4/5 + (-3/5) = -7/5 = -1 2/5;
3) -5/9 + (-4/9) = -9/9 = -1;
4) -2 1/3 + (-1/3) = -2 2/3;
5) -3 2/7 + (-1 1/7) = -4 3/7;
6) -5 4/5 + (-2 3/5) = -7 7/5 = -8 2/5;
7) -2/3 + (-1/6) = -4/6 + (-1/6) = -5/6;
8) -3/4 + (-5/6) = -9/12 + (-10/12)= -19/12 = -20 7/12;
9) -2/3 + (-3/5) = -10/15 + (-9/15) = -19/15 = -30 4/15;