27:[26+(6×a-7×3):9]+(13-2×2×3)=2

Răspuns :

27:[26+(6×a-7×3):9]+(13-2×2×3)=2
27:[26+(6×a-21):9]+(13-12)=2
27:[26+(6×a-21):9]+1=2
27:[26+(6×a-21):9]=2-1
27:[26+(6×a-21):9]=1
26+(6×a-21):9=1×27
26+(6×a-21):9=27
(6×a-21):9=27-26
(6×a-21):9=1
6×a-21=1×9
6×a-21=9
6×a=9+21
6×a=30
a=30:6
a=5