Răspuns :
15 :[11-(7×5-9×9:x:3) :8+2×4]×3=3
[11-(35-27:x) :8+8]=15
-(35-27:x) :8=15-19
(35-27:x) :8=4
35-27:x =32
3=27:x
x=9
[11-(35-27:x) :8+8]=15
-(35-27:x) :8=15-19
(35-27:x) :8=4
35-27:x =32
3=27:x
x=9