11supra2-12supra2:(5supra2-4supra2)

Răspuns :

11/2-12/2:(5/2-4/2)=
=11/2-12/2:1/2=
=11/2-(12x2/2x1)=
=11/2-(24/2)=
=11/2-12/1=
=11/2-24/2=
=-13/2

sper sa fie bine