−5 + (−3) = −(5 + 3) = −8;
−8 + (−9) = −(8 + 9) = −17;
−0,5 + (−0,7) = −(0,5 + 0,7) = −1,2;
12 + (−8) = 12 − 8 = 4;
−12 + 8 = −(12 − 8) = −4;
5 + (−3) = 5 − 3 = 2;
−8 + 9 = 9 − 8 = 1;
−0,5 + 0,3 = −(0,5 − 0,3) = −0,2;
−12 + 12 = 12 − 12 = 0;
0 + (−5) = −(5 − 0) = −5.