1+{2•[3+(a•b•c-4)•5]:6}•7=78
{2•[3+(a•b•c-4)•5]:6}•7=78 - 1
{2•[3+(a•b•c-4)•5]:6}•7= 77
2•[3+(a•b•c-4)•5]:6 = 77:7
2•[3+(a•b•c-4)•5]:6 = 11
2•[3+(a•b•c-4)•5] = 11×6
2•[3+(a•b•c-4)•5] = 66
3+(a•b•c-4)•5]= 66:2
3+(a•b•c-4)•5 = 33
(a•b•c-4)•5 = 33-3
(a•b•c-4)•5 = 30
a•b•c-4 = 30 : 5
a•b•c-4 = 6
a•b•c = 6+4
a•b•c = 10
1×2×5 = 10 ; 5×2×1=10...
10×1×1 = 10; 1×10×1 = 10..
a = {1;2;5;10}
b= {1;2;5;10}
c = {1;2;5;10}