Răspuns :
7-(18-2):6=[8-3×(9-7)]× a
7-16:6=(8-3×2)× a
7-16:6=(8-6)× a
7-16:6=2a
7-2,(6)=2a
4,(3)=2a
a=2,1(6)
sau a= 13/6
7-16:6=(8-3×2)× a
7-16:6=(8-6)× a
7-16:6=2a
7-2,(6)=2a
4,(3)=2a
a=2,1(6)
sau a= 13/6