Răspuns :
5+[16-(9:a×8+7)]×6=11
[16 - (9 : a x 8 + 7)] x 6 = 11 - 5
[16 - (9 : a x 8 + 7)] x 6 = 6
16 - (9 : a x 8 + 7) = 6 : 6
16 - (9 : a x 8 + 7) = 1
9 : a x 8 + 7 = 16 - 1
9 : a x 8 + 7 = 15
9 : a x 8 = 15 - 7
9 : a x 8 = 8
9 : a = 8 : 8
9 : a = 1
a = 9 : 1
a = 9