a) a-(b-c)=2-(4-6)=2-(-2)=2+2=4
b) a-(b-c)= -1-(5-7)=-1-(-2)=-1+2=1
c) a-(b-c)=10-(-8-9)=10-(-17)=10+17=27
d) a-(b-c)=6-[8-(-11)]=6-(8+11)=6-19=-13
e) a-(b-c)= -12-(-14-6)=-12-(-20)=-12+20=8
f) a-(b-c)= -11-[4-(-19)]=-11-(4+19)=-11-23=-34
g) a-(b-c)=12-[-27-(-5)]=12-(-27+5)=12-(-22)=12+22=34
h) a-(b-c)=-6-[-3-(-15)]=-6-(-3+15)=-6-12=-18
i) a-(b-c)=0-(-5-25)=0-(-30)=0+30=30
