a.-12+9-15+23)=-12+8=-4
b.(-7+11)-(-15)=3+15=18
c.-1/3+1/2=-2+3/totul supra6=1/6(am amplificat)
d.-3/5-7/3=-6-35/totul supra15=-41/15(am amplificat)
e.(-4)x(-15+17)=-4x2=-8
f.(-2la a 20x(-7+12)=4x5=20
g.2/1/3-3/1/2=2x3-3x2=6-6=0
h.(-1)la a5x(-2 la a3+13)=-1x(-8+13)=-1x5=-5
i.2/7+2-4/3=6+42-28/totul supra21=20/21
