3505

-8,34+(-6,88)+8,34+9,88=-8,34-6,88+8,34+9,88=(-8,34 и 8,34 сокращаются)

=-6,88+9,88=3

-9,59+3,26+6,59+(-1,26)=-9,59+3,26+6,59-1,26=(-9,59+6,59)+(3,26-1,26)=-3+2=-1

3506

1)-27 + 14 + (-80) + 21 + (-28) = -100;

-27 + 14 = -13;

-13 + (-80) = -93;

-93 + 21 = -72;

-72 + (-28) = -100;

2) -3,27 + (-4,84) + 6,51 + (-2,64) + 7,65 = 3,41.

-3,27 + (-4,84) = -8,11;

-8,11 + 6,51 = -1,6;

-1,6 + (-2,64) = -4,24;

-4,24 + 7,65 = 3,41.