Question

polinomios aritmeticos:
1) -(-20-31)-[6+(2-15)]
2) -20+[15-(7-12)]+4
3) - [6-(8+5)+(4-9)]-7
4) -11- {2+[5-(6-7+3)]+12}-1
5) -[-{[(+3)+(-2)]-[(-5)+(-9)]}]

Answer 1

1) -(-20-31)-[6+(2-15)]
   -(-51)-(6-13)=51+7=58
2) -20+[15-(7-12)]+4
-20+(15+5)+4=4
3) - [6-(8+5)+(4-9)]-7
   -(6-13-5)-7=12-7=5
4) 11- {2+[5-(6-7+3)]+12}-1
    11-[2+(5-2)+12]-1=11-17-1=-7
5) -[-{[(+3)+(-2)]-[(-5)+(-9)]}]
-[-{(3-2)-(-14)}]=-[-(1+14)]=15