Question

20-{8+[3+(8-5)-1]+6}

Answer 1

20-{8+[3+(8-5)-1]+6}=
20-{8+[3+3-1]+6}=
20-{8+[6-1]+6}=
20-{8+5+6}=
20-{13+6}=
20-19 =
= 1

Answer 2

20-{8+[3+3-1]+6}
20-{8+5+6}
20-19 = 1