Răspuns :
(ax7:2+4x7):6=7
(ax7:2+28)=7x6
ax7+28=42
ax7=42-28
ax7=14
a=14:7
a=2
(ax7:2+28)=7x6
ax7+28=42
ax7=42-28
ax7=14
a=14:7
a=2
(ax7:2+4x7):6=7
(ax7:2+28):6=7
ax7:2+28=6x7=42
ax7:2=42-28=14
ax7=14x2=28
a=28:7
a=4
(ax7:2+28):6=7
ax7:2+28=6x7=42
ax7:2=42-28=14
ax7=14x2=28
a=28:7
a=4