1/2 : (1 - 1/2) : [1/5 + 4×(1/3+1/3:2)]+1/11 =
= 1/2 : 1/2 : [1/5 + 4×(1/3+1/3×1/2)] + 1/11 =
= 1/2 × 2 : [1/5 + 4×(1/3 + 1/6)] + 1/11 =
= 2/2 : ( 1/5 + 4 × 3/6) + 1/11 =
= 1 : ( 1/5 + 12/6) + 1/11 =
= 1 : ( 1/5 + 2) + 1/11 =
= 1 : 11/5 + 1/11 =
= 1 × 5/11 + 1/11 =
= 5/11 + 1/11 =
= 6/11