6) 12+(-4)= -24+11= 65+(-45)= 7) 200+83= 19+(-8)+(-2)= -9+(-9)+(-9)=

1. $$ 12 + (-4) = 8 $$
2. $$ -24 + 11 = -13 $$
3. $$ 65 + (-45) = 20 $$
4. $$ 200 + 83 = 283 $$
5. $$ 19 + (-8) + (-2) = 19 - 8 - 2 = 11 - 2 = 9 $$
6. $$ -9 + (-9) + (-9) = -9 - 9 - 9 = -27 $$

Ответ: смотри решение