Question

{[-(12-4.8):(7.4-6.5)+17]. (4+2.3)-55}:3

Answer 1

{[-(12-32) : (28-30) + 17] . (4+6) -55} :3
{[- (-20) : (-2) + 17] . 10-55}:3
[(+20:2) + 17 . -45]:3
[10+17 . -45] :3
[27 . -45]:3
-1215:3
-405