4 - { 3 + 77 : [ 3 × ( b + 5 ) - 7 ] } : 10 = 3
{ 3 + 77 : [ 3 × ( b + 5 ) - 7 ] } : 10 = 4 - 3
{ 3 + 77 : [ 3 × ( b + 5 ) - 7 ] } : 10 = 1
3 + 77 : [ 3 × ( b + 5 ) - 7 ] = 1 × 10
3 + 77 : [ 3 × ( b + 5 ) - 7 ] = 10
77 : [ 3 × ( b + 5 ) - 7 ] = 10 - 3
77 : [ 3 × ( b + 5 ) - 7 ] = 7
3 × ( b + 5 ) - 7 = 77 : 7
3 × ( b + 5 ) - 7 = 11
3 × ( b + 5 ) = 11 + 7
3 × ( b + 5 ) = 18
b + 5 = 18 : 3
b + 5 = 6
b = 6 - 5
b = 1
