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+5+6}
20-19
1

Answer 2

Boa noite.

20-{8+[3+(8-5)-1]+6}  =

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

Bons estudos! :-)