Question

 quanto é ?      -(-23+19-1)-{3-(4+7-15)]

Answer 1

(+23-19+1)-{-12-21+45}
(4+1)-{-33+45}
5-{12}
5-12
-7

Answer 2

 -(-23+19-1)-[3-(4+7-15)]
-(-24 +19) -[ 3 -(11 -15)]
+24 -19 -[3- 11 +15]
24 -19 -3 +11 -15
24 +11 -19 -3 -15
35 - 37
-2